KR20110121472A - Monitoring method and device for continuous casting of near net shape billet - Google Patents

Abstract

PURPOSE: A method and a device for monitoring an electromagnetic continuous casting facility for a free cross section material are provided to extract the most accurate and optimized casting conditions about cooling water amount, casting speed, and applied electromagnetic field from temperatures that are measured in real time by a thermocouple installed in a mold. CONSTITUTION: A method for monitoring an electromagnetic continuous casting facility for a free cross section material is as follows. A thermocouple(10) is installed in a mold(100) of an electromagnetic continuous casting facility for billet having a free cross section and measures the internal temperature of the mold in real time. The appropriateness of cooling water amount, casting speed, and applied electromagnetic field for each portion of the mold is determined from the measured temperature data. The cooling water amount, casting speed, and applied electromagnetic field are controlled according to the determination result.

Description

MONITORING METHOD AND DEVICE FOR CONTINUOUS CASTING OF NEAR NET SHAPE BILLET}

The present invention relates to a facility for electromagnetic continuous casting of billets of free cross-sectional shape. More specifically, the present invention relates to a method and apparatus for monitoring a free-form section electromagnetic continuous casting facility which is capable of deriving optimal casting conditions in continuous casting.

In general, as a continuous casting technique of a round billet, DC casting (Direct Chill Casting), Hot Top casting and Air slip casting are widely used. The DC casting method is a method of installing a chill mold at a predetermined depth at a predetermined interval and injecting molten metal into the solid mold. However, there is a problem of casting speed limitation and billet surface quality due to cooling by direct contact between the melt and the chill mold. Hot Top Casting is a method developed to suppress the air gap generated by the DC casting method. The molten metal is injected horizontally with less turbulence through the heat insulating head. Hot top casting method has the advantage of minimizing the confusion of the molten metal by installing a refractory head on top of the male mold, and there is no mixing of gas or inclusions.

The recently developed air-slip casting method is a method for increasing casting speed and reducing billet surface defects by installing a porous graphite ring between a hot top and a mold and injecting air and oil to initiate an initial solidification shell. This technology improves the surface quality by lowering the cooling speed of the part.

The above billet casting technique was developed for increasing the casting speed and improving the surface quality of the billet, but it is difficult to control the internal quality, that is, the equiaxed crystal, which is advantageous for the post processing.

Recently, a technique for simultaneously improving surface quality and internal quality by applying an electromagnetic field has been proposed. Billet manufacturing technology using the electromagnetic field can improve the speed and surface quality, which is an advantage of the existing technology, as well as agitation using the electromagnetic field, so that the internal quality, that is, the equiaxed crystal region inside the billet, can be expected to improve the quality. High-frequency electromagnetic fields control surface cooling to induce quality improvements, while low-frequency electromagnetic fields enhance melt flow to achieve internal quality improvements.

In order to apply the electromagnetic stirring technology for improving the internal quality of the electromagnetic continuous casting technology, it is necessary to establish the optimal process conditions such as optimization of the cooling water amount, optimization of the casting speed and the electromagnetic field.

Recently, the trend of continuous casting technology of billets has been expanded from circular to billets having a free cross-sectional shape. In particular, optimal process conditions are required when manufacturing billets having a free cross-sectional shape.

For example, parts that require free cross-sectional shapes made of aluminum or magnesium, such as automotive low arms, cannot be manufactured by casting because they require high mechanical properties. Accordingly, when the low arm is manufactured through multi-step forging through the extrusion or rolling process after manufacturing a billet having a free cross-sectional shape by electromagnetic continuous casting, it may solve the problem of low productivity or high manufacturing cost. However, this requires control of surface solidification and internal quality improvement during billet casting.

Accordingly, in manufacturing a billet having a free cross-sectional shape by electromagnetic continuous casting, it is required to establish optimum process conditions and quantify optimal process variables.

Accordingly, the method for monitoring the electromagnetic continuous casting facility of the free-form shape member which detects the temperature distribution of the molten metal in the mold and optimizes the amount of cooling water in each part of the mold having the free-sectional shape and optimizes the casting speed and the applied electromagnetic field. Provide a monitoring device.

In addition, the present invention provides a method and a monitoring apparatus for an electromagnetic continuous casting facility for monitoring a free cross-sectional shape member which is capable of manufacturing a billet having a free cross-sectional shape at high quality and at high speed through quantification of process variables during continuous casting.

To this end, the present method measures the temperature in the mold in real time by installing a thermocouple in a mold of an electromagnetic continuous casting facility for continuously casting a billet having a free cross-sectional shape, and according to the measured temperature data, each part of the mold having a free cross-sectional shape. The cooling water amount, the casting speed, and whether the applied electromagnetic field is appropriately determined may be adjusted to adjust the cooling water amount, the casting speed, and the applied electric field.

In this case, the temperature measurement in the mold may be performed on the outwardly convex portion and the inwardly concave portion of the free cross-sectional shape of the mold.

In addition, the temperature measurement in the mold may be measured at a plurality of places at intervals along the vertical direction of the mold.

In addition, the temperature measurement in the mold may be measured on the inner side and the outer side of the mold along the thickness direction of the mold.

Determination of the cooling water amount, casting speed and the appropriate application of the electromagnetic field can be made by calculating the temperature deviation of the inner and outer sides with respect to the thickness direction of the mold and the deviation of the temperature with respect to the longitudinal direction in each part of the mold.

In this way, by checking the temperature distribution of the mold based on the thermocouple temperature, it is possible to detect whether the molten metal is cooled in the mold, to predict the depth of the molten metal, and to confirm the effective application of the electromagnetic field. This will be able to optimize the casting conditions.

The apparatus includes a thermocouple installed in a mold of an electromagnetic continuous casting facility for continuously casting a billet having a free cross-sectional shape in real time, a data section for storing temperature data measured from the thermocouple, and a data section. The temperature value may be calculated to obtain a heat transfer deviation in the mold, and the controller may control the electromagnetic continuous casting facility according to the deviation value.

The thermocouple may be installed in the convex portion and the concave portion of the mold having a free cross-sectional shape.

In addition, the thermocouple may be installed in a plurality of places at intervals in the vertical direction of the mold in the convex portion or concave portion may be a structure for detecting the temperature in the vertical direction of the mold.

In addition, the thermocouple may be provided in a convex portion or a concave portion at intervals in the thickness direction of the mold to detect a temperature inside and outside the mold.

As described above, according to the present embodiment, the most accurate and optimized casting conditions for the amount of cooling water, the casting speed, and the applied electric field are derived and applied to the production industry by the temperature values detected in real time by the thermocouple installed in the mold. This makes it possible to optimize the operating conditions.

Therefore, it is possible to quantify the process variables in the electromagnetic continuous casting process, and based on this, it is possible to manufacture a healthy, high quality free cross-section billet at high speed without breakout by continuously adjusting the process conditions.

1 is a schematic view showing an electromagnetic continuous casting plant according to the present embodiment.
2 is a perspective view illustrating a mold for electromagnetic continuous casting of a free cross-sectional shape member according to the present embodiment.
3 is a schematic diagram illustrating a thermocouple installed in a mold according to this embodiment.
4 and 5 are views of a billet manufactured according to the prior art and a billet having a free cross-sectional shape manufactured according to the present embodiment.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As can be easily understood by those skilled in the art, the embodiments described below may be modified in various forms without departing from the concept and scope of the present invention. Where possible the same or similar parts are represented with the same reference numerals in the drawings.

All terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

In the following description, a case of continuously casting an aluminum billet with a free cross-sectional shape member will be described as an example. However, the present invention is not limited to this and will be applicable to the case of manufacturing the billet of the free cross-sectional forming material for all metals except aluminum.

1 is a schematic diagram showing an electromagnetic continuous casting plant according to the present embodiment.

According to the above drawings, the electromagnetic continuous casting facility of the continuous casting mold 100 for solidifying the molten aluminum, the electromagnetic coil 110 for applying a high frequency current provided outside the mold 100, the mold 100 The low frequency electromagnetic stirring device 120 installed in the lower portion, the mold cooling unit 130 for cooling the mold 100, the slab cooling unit 140 for cooling the cast steel, the casting solidified from the mold 100 It includes a peripheral speed control unit 150 for controlling the convenience withdrawal speed.

When a high frequency current is applied to the electromagnetic coil 110, an induction magnetic field and a current are generated in the molten aluminum inside the mold 100. The induced current not only heats the molten metal but also interacts with the magnetic field to generate electromagnetic forces in the molten metal. The electromagnetic force increases the surface curvature of the molten metal in contact with the mold 100 and reduces the contact pressure between the cast steel and the mold 100. By heating, the surface of the molten metal is heated intensively and the rate of solidification can be controlled to obtain a small latent heat of solidification, and continuous casting can be performed without defects due to solidification unevenness and rapid cooling.

The low frequency electromagnetic stirring device 120 is located at the lower side of the mold 100 to stir the molten metal for internal quality control. When the molten metal in the mold 100 is rotated in the circumferential direction with the rotary electromagnetic stirring device 120, the columnar crystal structure is cut to obtain the cast steel in which the entire cast piece becomes an equiaxed crystal structure and the cast structure is refined.

As shown in FIG. 2, the casting mold 100 has a slit 102 for applying an electromagnetic field to the mold 100. In addition, since the mold 100 has a free cross-sectional shape rather than a circular shape, a part protruding outwardly and a part recessed inwardly exist. For convenience of explanation, the portion protruding outwardly is called the convex portion 104, and the portion penetrated inwardly is called the recessed portion 106.

Here, in the continuous casting facility, the apparatus measures the temperature in the mold 100 in real time, compares the measured temperature, and derives an optimized casting condition to control the components.

To this end, the apparatus is installed in the mold 100, the thermocouple 10 for measuring the temperature in the mold 100, and the data unit 20 for storing the temperature data measured from the thermocouple 10, therein And a control unit 30 having data on a set operation condition, comparing the data with the data applied through the data unit 20 to obtain an optimized value, and controlling and controlling the electromagnetic continuous casting facility according to the value. .

The most important factor in continuous casting of the billet of the free cross-sectional shape is the measured temperature in the mold 100 of the performance equipment. It is very important to obtain very accurate temperature data in order to obtain optimum casting conditions for continuous casting equipment.

In this embodiment, as shown in FIG. 3, the thermocouple 10 for temperature measurement is installed at 20 sites in the mold 100 to measure the temperature in the mold 100.

In the present embodiment, the thermocouple 10 is installed at two points of the mold 100, and 20 are installed in each of the ten points. Here, the two points where the thermocouple 10 is installed may be set as the convex portion 104 and the concave portion 106 of the mold, respectively. In addition, 10 thermocouples may be additionally installed by setting an intermediate portion between the convex portion and the concave portion for the accuracy of the operating conditions. At one point, the thermocouple is selected at five places with a predetermined interval in the vertical direction of the mold 100, and selected by installing two places in the thickness direction. That is, at each point, ten thermocouples are arranged in pairs at intervals on a hot face and a cold face of the mold at the same height along the vertical direction of the mold. In addition, the thermocouple 10 is five pairs are arranged at regular intervals along the vertical direction of the mold 100, respectively. Since the mold 100 is formed with a slit 102, the thermocouple 10 is installed outside the position of the slit so that there is no interference with heat transfer. The paired thermocouples 10 located at the same height in the vertical direction of the mold may be disposed on the same vertical axis, and may be disposed on different vertical axes, spaced apart by a predetermined angle, as shown in FIG. 3. . Even when the thermocouples 10 are spaced apart by a predetermined angle, the thermocouple 10 may be regarded as the same point and may be monitored because there is no significant difference compared with the case where the thermocouples 10 are disposed on the same axis. Two thermocouples installed at the same depth in the thickness direction of the mold are arranged at even intervals with respect to the thickness of the mold. For example, when the thickness of the mold is 10mm, the two thermocouples 10 may be positioned at about 4mm and 7mm respectively from the inner circumferential surface of the mold 100. The thermocouple on the inner side of the two thermocouples respectively measures the temperature of the molten metal and the proximity region, and the outer thermocouple can calculate the deviation by measuring the temperature of the cooling water and the proximity region.

The thermocouple 10 is electrically connected to the data unit 20 to output the measured value to the data unit 20. The data unit 20 is electrically connected to the control unit 30 to output the input temperature data value to the control unit 30.

The control unit 30 is electrically connected to the electromagnetic coil 110 and the electromagnetic stirring device 120, the mold cooling unit 130, the slab cooling unit 140 and the peripheral speed control unit 30 of the electromagnetic continuous casting facility, The control unit is operated.

In addition, the control unit 30 includes a calculation unit for calculating the heat transfer deviation for each point of the mold by calculating the measured data applied from the data unit 20. The calculation formula stored in the calculation unit of the control unit 30 may vary depending on facility conditions, and the like, and optimal casting conditions may be obtained through actual temperature values measured through the thermocouple 10 installed in the mold 100 as in the present embodiment. If it can obtain, it will not specifically limit.

Hereinafter, looking at the process of optimizing the casting conditions by the apparatus as follows.

The molten aluminum is manufactured as a cast while moving at a constant speed under the control of the circumferential speed controller 30 in the mold 100.

In this process, the temperature data measured on the thermocouple 10 installed in the mold 100 is applied to the data unit 20 and stored in real time. That is, the inner thermocouple of each thermocouple installed in the mold measures the temperature of the molten metal and the proximity region, respectively, and the outer thermocouple measures the temperature of the cooling water and the proximity region.

The control unit 30 calculates the deviation by calculating the measured values of the thermocouples, and grasps the degree of heat transfer based on the deviation.

The controller 30 determines the degree of heat transfer at each point installed along the vertical direction, starting from the molten surface on which the thermocouple is installed. The heat transfer degree rises from the molten surface to the lower point, and as the depth increases, an air layer is formed between the solidified surface and the mold, which reduces the heat transfer and tends to decrease the deviation.

The controller 30 displays the heat transfer profile in real time through the data unit 20 and stores the heat transfer profile at predetermined time intervals. The control unit determines whether or not the cooling is sufficiently cooled through the mold based on the heat transfer profile, it is possible to optimize the amount of cooling water.

That is, the controller calculates the profile deviation at each point by calculating the profile according to the real-time temperature measurement value stored in the data unit 20. The controller 30 derives an optimal operating condition based on the calculated result. Accordingly, the controller 30 calculates an optimized value of the amount of cooling water, the casting speed, and the current applied to the electromagnetic coil 110 and the electromagnetic stirring device 120 according to the temperature value at each point of the mold 100 that is actually measured. Will be derived.

Accordingly, the controller 30 controls the electromagnetic coil 110 and the electromagnetic stirring device 120 of the electromagnetic continuous casting facility to optimize the electromagnetic stirring conditions. Similarly, the control unit 30 controls the mold cooling unit 130 and the slab cooling unit 140 to adjust the amount of cooling water, and controls the circumferential speed control unit 150 to adjust the extraction speed of the cast steel. In addition, when the temperature of the tundish is also monitored in the temperature measurement, it is possible to easily determine whether there is an abnormality in the process variable, thereby preventing early break-out.

Thus, the depth of the melt can be estimated based on the temperature of each thermocouple, and the electromagnetic field application conditions, the amount of cooling water, and the withdrawal rate of the cast steel which have a great influence on the surface quality of the aluminum billet can be adjusted by the temperature distribution in the mold 100. It is. In addition, electromagnetic stirring conditions, which are factors affecting the internal quality of billets, may be optimized by predicting the depth of melt in the mold according to the mold temperature distribution.

In addition, in the present embodiment, the monitoring of the convex part 104 and the concave part 106 of the mold allows the amount of cooling water to be adjusted to the shape even in the case of a mold having a free cross-sectional shape.

The convex portion 104 of the mold having the free cross-sectional shape is close to the cooling water and the heat transfer area is large, causing rapid solidification. On the contrary, the fouling portion 106 is relatively far from the cooling water and is slowly cooled since heat transfer is not easy. This non-uniform coagulation can lead to poor surface quality and breakout during operation.

The controller 30 may adjust the amount of cooling water locally to measure the temperature from the thermocouple 10 installed in both the convex portion 104 and the concave portion 106 of the mold and calculate the same so that the same solidification occurs on the front surface of the mold. It is.

[Example]

4 and 5 show a cross section of a free cross-sectional shape billet of an aluminum alloy having a cross-sectional area of 175 cm 2. The billet was manufactured at a casting speed of 10 Cm / min through a free cross-section electromagnetic continuous casting facility, and the amount of cooling water was locally controlled to inject several tens of liters of cooling water per minute.

Figure 5 shows a free cross-sectional billet cast when the same amount of cooling water is injected throughout the mold. As shown, the convex portion of the billet may be cooled to obtain a healthy surface quality, but the concave portion may proceed to a state in which solidification is not completed, indicating that unnecessary tissue is formed by further deformation and melt leakage.

On the other hand, Figure 4 shows a billet of the free cross-sectional shape manufactured by the apparatus. The billet was manufactured by measuring the temperature deviation of the convex portion and the recessed portion of the mold through the present apparatus, and calculating the measured value to adjust the amount of cooling water so that there is no temperature deviation. That is, a large amount of cooling water was injected into the recesses of the mold through the apparatus, and the amount of cooling water was reduced in the convex parts.

As a result, as shown in Figure 4, it can be seen that the billet can be cast in a whole healthy shape, both convex portion and concave portion despite the manufacture of the billet of the free cross-sectional shape.

While the illustrative embodiments of the present invention have been shown and described, various modifications and alternative embodiments may be made by those skilled in the art. Such variations and other embodiments will be considered and included in the appended claims, all without departing from the true spirit and scope of the invention.

10: thermocouple 20: data portion
30:

Claims (9)

A thermocouple is installed in a mold of an electromagnetic continuous casting facility for continuously casting a billet having a free cross-sectional shape to measure the temperature in the mold in real time, and the amount of cooling water for each part of the free cross-sectional mold according to the measured temperature data, A method for monitoring electromagnetic continuous casting equipment of free-form shape member which controls the amount of cooling water, casting speed and applied electric field by judging casting speed and proper electromagnetic field. The method of claim 1,
The temperature measurement in the mold is a method of monitoring a free-form cross-section electromagnetic continuous casting equipment made of the outward convex portion and the inward concave portion of the free cross-sectional shape of the mold. The method of claim 2,
The temperature measurement in the mold is a method of monitoring the electromagnetic continuous casting equipment of the free-form shape member made in a plurality of places at intervals along the vertical direction of the mold. The method of claim 3, wherein
The temperature measurement in the mold is a method of monitoring the electromagnetic continuous casting equipment of the free-form shape member made on the inner side and the outer side of the mold along the thickness direction of the mold. The method of claim 4, wherein
The determination of the amount of cooling water, casting speed, and application of the applied electromagnetic field is performed by calculating the temperature deviation of the inside and outside of the mold in the thickness direction and the temperature deviation of the mold in the longitudinal direction. Casting facility monitoring method. A thermocouple installed in a mold of an electromagnetic continuous casting facility for continuously casting a billet having a free cross-sectional shape and measuring a temperature in the mold in real time;
A data unit for storing temperature data measured from the thermocouple;
A control unit for calculating a heat transfer deviation in a mold by calculating a temperature value of the data unit and controlling and operating the electromagnetic continuous casting machine according to the deviation value
Electromagnetic continuous casting equipment monitoring device comprising a free cross-sectional shape member comprising a. The method according to claim 6,
The thermocouple is a free-form cross-section electromagnetic continuous casting equipment monitoring device installed in the convex portion and the recess of the mold having a free cross-sectional shape. The method of claim 7, wherein
The thermocouple is installed in a plurality of locations at intervals in the vertical direction of the mold in the convex portion or concave portion is a free cross-sectional shape electromagnetic continuous casting facility monitoring device having a structure for detecting the temperature in the vertical direction of the mold. The method of claim 8,
The thermocouple is installed in the convex portion or concave portion at intervals in the thickness direction of the mold free cross-sectional shape member electromagnetic continuous casting equipment monitoring device having a structure for detecting the temperature inside and outside the mold.

Images