KR101159613B1

KR101159613B1 - Apparatus for distinguishing taper of mold in continuous casting and method for distinguishing taper in continuous casting

Info

Publication number: KR101159613B1
Application number: KR1020100028638A
Authority: KR
Inventors: 권효중; 최주태; 하태준
Original assignee: 현대제철 주식회사
Priority date: 2010-03-30
Filing date: 2010-03-30
Publication date: 2012-06-27
Also published as: KR20110109085A

Abstract

The present invention provides a mold formed by solidifying and discharging a portion of the molten steel that is introduced by having two pairs of walls forming an internal cavity, and measuring a temperature of the mold installed with respect to the mold and changed by the molten steel. The present invention provides a taper discrimination apparatus for a continuous casting mold, and a method for identifying the same, comprising a measuring unit and a determining unit for determining whether the taper of the walls of the mold is appropriate based on a temperature value measured by the measuring unit.

Description

Apparatus and method for determining taper of continuous casting molds {APPARATUS FOR DISTINGUISHING TAPER OF MOLD IN CONTINUOUS CASTING AND METHOD FOR DISTINGUISHING TAPER IN CONTINUOUS CASTING}

The present invention relates to an apparatus for determining the taper degree of a mold of continuous casting and a method of determining the same.

In general, a continuous casting machine is a facility for producing slabs of a constant size by receiving a molten steel produced in a steelmaking furnace and transferred to a ladle in a tundish and then supplying it as a mold for a continuous casting machine.

The continuous casting machine includes a ladle for storing molten steel, a continuous casting machine mold for cooling the tundish and the molten steel discharged from the tundish to form a casting having a predetermined shape, and the casting formed in the mold connected to the mold to move. It includes a plurality of pinch rollers.

In other words, the molten steel tapping out of the ladle and tundish is formed of a slab (Slab) or bloom (Bloom), billet (Billet) having a predetermined width and thickness in the mold and is transferred through the pinch roller.

An object of the present invention is to provide an apparatus and method for determining the taper of a continuous casting mold which can determine whether the taper set for the mold in the continuous casting process is appropriate according to the process.

The taper discrimination apparatus of the continuous casting mold according to the embodiment of the present invention for realizing the above object is provided with a mold formed to solidify and discharge a part of the molten steel that is provided with two pairs of walls forming an internal cavity; A measuring unit for measuring the temperature of the mold, which is installed with respect to the mold and changed by the molten steel, and a determination unit for determining whether the taper of the walls of the mold is appropriate based on the temperature value measured by the measuring unit. It includes.

The measuring unit may be arranged at the corner portion where adjacent walls of the mold meet.

The measuring unit comprises a plurality of sensors, which may be arranged along the circumferential direction of the mold.

The sensors may be arranged in rows from one of the two adjacent walls to the other.

The determination unit may determine whether the taper is appropriate by comparing the measured temperature value with a reference value.

The determination unit may determine whether the taper is appropriate by comparing the measured temperature value with the reference value of the temperature of the mold according to the casting speed.

According to another aspect of the present invention, there is provided a taper determination method for a continuous casting mold, the method comprising: measuring a temperature pattern along a circumferential direction of a mold to which molten steel is solidified; comparing the measured temperature pattern with a reference pattern; Determining whether the taper of the walls of the mold is appropriate from the comparison result.

The mold is formed by a plurality of walls, at least one of which may be arranged with two or more sensors for temperature measurement.

The reference pattern may be a temperature distribution by a plurality of sensors.

The method may further include informing a determination result of the degree of the taper or adjusting the taper according to the determination result.

According to the taper determination apparatus and method of the continuous casting mold which concerns on this invention comprised as mentioned above, it becomes possible to discriminate whether the taper set with respect to a mold is suitable according to the change of the conditions in a continuous casting process.

The result of this determination can be information for quick adjustment of the taper of the mold.

1 is a side view showing a continuous casting machine according to an embodiment of the present invention,
2 is a conceptual diagram illustrating the continuous casting machine of FIG. 1 based on the flow of molten steel (M),
3 is a conceptual diagram illustrating a distribution form of molten steel M in the mold 30 and the adjacent portion of FIG. 2,
FIG. 4A is a schematic plan view of the mold 30 of FIG. 3, FIG. 4B is an enlarged view of a corner portion A of the mold 30 of FIG. 4A,
FIG. 5A is a plan view illustrating a case in which the taper of the mold 30 is insufficiently changed in FIG. 4B.
5B is a plan view showing a case in which the taper of the mold 30 is excessively changed in FIG. 4B,
FIG. 6 is a graph showing a distribution of temperature values of the end wall 32 of the mold 30 measured by nine sensors installed on the end wall 32 in the case of FIGS. 4B and 5A.
7 is a graph showing the correlation between the casting speed and the mold 30 temperature, which can determine the appropriateness of the taper according to the casting speed,
8 is a flow chart for explaining a method of determining the taper of the continuous casting associated with another embodiment of the present invention.

Hereinafter, an apparatus and method for determining a taper of a continuous casting mold according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the present specification, different embodiments are given the same or similar reference numerals for the same or similar configurations, and the description is replaced with the first description.

Continuous casting is a casting method in which a casting or steel ingot is continuously extracted while solidifying molten metal in a mold without a bottom. Continuous casting is used to manufacture simple products such as squares, rectangles, circles, and other simple cross-sections, and slab, bloom and billets, which are mainly for rolling.

The type of continuous casting machine is classified into vertical type, vertical bending type, vertical axis difference bending type, curved type and horizontal type. 1 and 2 illustrate a curved shape.

1 is a side view showing a continuous casting machine related to an embodiment of the present invention.

Referring to this drawing, the continuous casting machine may include a tundish 20, a mold 30, secondary cooling tables 60 and 65, a pinch roll 70, and a cutter 90.

The tundish 20 is a container that receives molten metal from the ladle 10 and supplies molten metal to the mold 30. Ladle 10 is provided in a pair, alternately receives molten steel to supply to the tundish 20. In the tundish 20, the molten metal supply rate is adjusted to the mold 30, the molten metal is distributed to each mold 30, the molten metal is stored, and the slag and the non-metallic inclusions are separated.

The mold 30 is typically made of water-cooled copper and allows the molten steel to be primary cooled. The mold 30 forms a hollow portion in which molten steel is accommodated as a pair of structurally facing faces are opened. In manufacturing the slab, the mold 30 comprises a pair of barriers and a pair of end walls connecting the barriers. Here, the short wall has a smaller area than the barrier. The walls of the mold 30, mainly short walls, may be rotated to move away from or close to each other to have a certain level of taper. This taper is set to compensate for shrinkage caused by solidification of the molten steel M in the mold 30. The degree of solidification of the molten steel (M) will vary depending on the carbon content, the type of powder (steel cold Vs slow cooling), casting speed and the like depending on the steel type.

The mold 30 has a strong solidification angle or solidifying shell 81 (see FIG. 2) so that the casting extracted from the mold 30 maintains its shape and does not leak molten metal which is still less solidified. It serves to form. The water cooling structure includes a method of using a copper pipe, a method of drilling a water cooling groove in the copper block, and a method of assembling a copper pipe having a water cooling groove.

The mold 30 is oscillated by the oscillator 40 to prevent the molten steel from sticking to the wall of the mold. Lubricants are used to reduce friction between the mold 30 and the casting during oscillation and to prevent burning. Lubricants include splattered flat oil and powder added to the molten metal surface in the mold 30. The powder is added to the molten metal in the mold 30 to become slag, as well as the lubrication of the mold 30 and the casting, as well as the oxidation and nitriding prevention and thermal insulation of the molten metal in the mold 30, and the non-metal inclusions on the surface of the molten metal. It also performs the function of absorption. In order to inject the powder into the mold 30, a powder feeder 50 is installed. The part for discharging the powder of the powder feeder 50 faces the inlet of the mold 30.

The secondary cooling zones 60 and 65 further cool the molten steel that has been primarily cooled in the mold 30. The primary cooled molten steel is directly cooled by the spray 65 spraying water while maintaining the solidification angle by the support roll 60 so as not to deform. Casting solidification is mostly achieved by the secondary cooling.

The drawing device adopts a multidrive method using a plurality of sets of pinch rolls 70 and the like so that the casting can be taken out without slipping. The pinch roll 70 pulls the solidified tip of the molten steel in the casting direction, thereby allowing the molten steel passing through the mold 30 to continuously move in the casting direction.

The cutter 90 is formed to cut continuously produced castings to a constant size. As the cutter 90, a gas torch, a hydraulic shear, or the like can be employed.

FIG. 2 is a conceptual view illustrating the continuous casting machine of FIG. 1 based on the flow of molten steel M. Referring to FIG.

Referring to this figure, the molten steel (M) is to flow to the tundish 20 in the state accommodated in the ladle (10). For this flow, the ladle 10 is provided with a shroud nozzle 15 extending toward the tundish 20. The shroud nozzle 15 extends to be immersed in the molten steel in the tundish 20 so that the molten steel M is not exposed to air and oxidized and nitrided. The case where molten steel M is exposed to air due to breakage of shroud nozzle 15 is called open casting.

Molten steel M in the tundish 20 flows into the mold 30 by an immersion nozzle 25 extending into the mold 30. The immersion nozzle 25 is disposed in the center of the mold 30 so that the flow of molten steel M discharged from both discharge ports of the immersion nozzle 25 can be symmetrical. The start, discharge speed, and stop of the discharge of the molten steel M through the immersion nozzle 25 are determined by a stopper 21 installed in the tundish 20 corresponding to the immersion nozzle 25. Specifically, the stopper 21 may be vertically moved along the same line as the immersion nozzle 25 to open and close the inlet of the immersion nozzle 25. Control of the flow of the molten steel M through the immersion nozzle 25 may use a slide gate method, which is different from the stopper method. The slide gate controls the discharge flow rate of the molten steel M through the immersion nozzle 25 while the sheet material slides in the horizontal direction in the tundish 20.

The molten steel M in the mold 30 starts to solidify from the part in contact with the wall surface of the mold 30. This is because heat is more likely to be lost by the mold 30 in which the periphery is cooled rather than the center of the molten steel M. The rear portion along the casting direction of the strand 80 is formed by the non-solidified molten steel 82 being wrapped around the solidified shell 81 in which the molten steel M is solidified by the method in which the peripheral portion first solidifies.

As the pinch roll 70 (FIG. 1) pulls the tip portion 83 of the fully solidified strand 80, the unsolidified molten steel 82 moves together with the solidified shell 81 in the casting direction. Uncondensed molten steel 82 is cooled by a spray 65 for spraying cooling water in the course of the above movement. This causes the thickness of the uncooled steel (82) in the strand (80) to gradually decrease. When the strand 80 reaches a point 85, the strand 80 is filled with the solidification shell 81 in its entire thickness. The solidified strand 80 is cut to a predetermined size at the cutting point 91 and divided into a product P such as a slab.

The form of the molten steel M in the mold 30 and the part adjacent to it is demonstrated with reference to FIG. FIG. 3 is a conceptual diagram illustrating a distribution form of molten steel M in the mold 30 and adjacent portions of FIG. 2.

Referring to FIG. 3, a pair of discharge ports 25a are typically formed at the end side of the immersion nozzle 25 on the left and right sides of the drawing (in the form of the mold 30 and the immersion nozzle 25, the center line C is formed). Assuming that the reference is symmetrical, only the left side is shown in this drawing}.

The molten steel M discharged together with the argon (Ar) gas from the discharge port 25a draws a trajectory flowing in the upward direction A1 and downward direction A2 as indicated by arrows A1 and A2. do.

The powder layer 51 is formed on the upper part of the mold 30 by the powder supplied from the powder supplier 50. The powder layer 51 may include a layer present in a form in which the powder is supplied and a layer sintered by the heat of the molten steel M (sintered layer is formed closer to the unsolidified molten steel 82). Below the powder layer 51, a slag layer or a liquid fluidized layer 52 formed by melting powder by molten steel M is present. The liquid fluidized bed 52 maintains the temperature of the molten steel M in the mold 30 and blocks the ingress of foreign matter. A portion of the powder layer 51 solidifies at the wall surface of the mold 30 to form a lubrication layer 53. The lubrication layer 53 functions to lubricate the solidified shell 81 so as not to stick to the mold 30.

The thickness of the solidification shell 81 becomes thicker as it progresses along the casting direction. The portion where the mold 30 of the solidification shell 81 is positioned is thin, and an oscillation mark 87 may be formed according to the oscillation of the mold 30. The solidification shell 81 is supported by the support roll 60, and the thickness thereof is thickened by the spray 65 for spraying water. The solidification shell 81 may be thickened, and a bulging region 88 may be formed in which a portion protrudes convexly.

FIG. 4A is a schematic plan view of the mold 30 of FIG. 3, and FIG. 4B is an enlarged view of a corner portion A of the mold 30 of FIG. 4A.

Referring to the drawings, a taper determination apparatus of a mold according to an embodiment of the present invention may include a mold 30, measurement units 100 and 200, and a determination unit 300.

The mold 30 is a hollow body that allows the molten steel M to solidify to have a substantially rectangular cross section. To this end, the mold 30 may be formed such that the pair of long walls 31 and the pair of end walls 32 face each other. The long wall 31 is formed to have a larger area than the short wall 32.

The end wall 32 may be pivoted in a direction T that rotates about its center line C. FIG. By turning the end wall 32, a taper may be set in the mold 30. This taper is for compensating the shrinkage amount due to the solidification of the molten steel M in the mold 30 as described above. If the taper is insufficient, the solidification shell 81 is deformed, so that the vertical crack is likely to occur in the corner portion. In addition, the possibility of cracking due to duty free at the center of the barrier 31 increases. When the taper is excessive, wear of the mold 30 may occur due to an increase in friction between the mold 30 and the solidification shell 81, or a corner crack may increase due to an increase in corner stress.

The long wall 31 rather than the end wall 32 may be pivoted for taper adjustment. However, rather than pivoting the long walls 31, it is usually the way to pivot the short walls 32.

The measuring units 100 and 200 are installed to measure the temperature of the set part of the long wall 31 and / or the short wall 32 of the mold 30. The temperature of the mold 30 will vary depending on the temperature of the molten steel M inside the mold 30.

The measuring units 100 and 200 can be installed on the long wall 31 or the short wall 32 as one sensor, for example a thermocouple. In the present embodiment, five sensors 110 to 150 and 210 to 250 are installed in the adjacent long wall 31 and the short wall 32 in order to grasp a more precise temperature distribution.

Five sensors 110 to 150 and 210 to 250 are disposed along the circumferential direction of the mold 30. They may be placed at the same height to form one row.

The judging unit 300 is configured to be electrically connected with the measuring units 100 and 200. The determination unit 300 determines whether the taper in the mold 30 is appropriate based on the temperature values measured from the measurement units 100 and 200.

Referring to FIG. 4B, the solidified shell 81, which is a solidified part of the molten steel M, is almost in close contact with the inner surface of the mold 30 while wrapping the uncondensed molten steel 82. This state is a case where the taper of the mold 30 is appropriately set according to the working conditions.

In this case, the distribution of the temperature values of the mold 30 measured by the measuring units 100 and 200 will be close to the reference distribution, and the determination unit 300 will determine that the taper is appropriate.

FIG. 5A is a plan view illustrating a case in which the taper of the mold 30 is insufficiently changed in FIG. 4B, and FIG. 5B is a plan view illustrating a case in which the taper of the mold 30 is excessively changed in FIG. 4B.

Referring to FIG. 5A, the solidification shell 81 is farther from the mold 30 than in the case of FIG. 4B. The degree of dropping above is maximized at the portion 312 where the long walls 31 and the short walls 32 meet.

In this case, in the measurement unit 100 of the barrier wall 31, the closer to the first sensor 110, the larger the temperature drop will be measured. In the measurement unit 200 of the end wall 32, the closer to the first sensor 210, the larger the temperature drop will be measured.

The determination unit 300 may determine that the taper of the mold 30 is insufficient based on the measurement result. The lack of taper may be due to a large shrinkage of the solidification shell 81 due to a decrease in casting speed, use of a hardened powder, or the like.

Referring to FIG. 5B, the solidification shell 81 comes into closer contact with the mold 30 than in the case of FIG. 4B.

As a result, buckling 81 ′ occurs in the solidification shell 81 at the barrier wall 31. By buckling 81 ', the temperature drop at the corresponding temperature sensor 130 will be large. In the remainder, it can be measured that the temperature has risen.

The determination unit 300 may determine that the taper of the mold 30 is excessive based on these measured values. Excessive taper may be due to the shrinkage of the solidification shell 81 due to an increase in casting speed, use of a slow cooling type powder, or the like.

FIG. 6 is a graph showing a distribution of temperature values of the end wall 32 of the mold 30 measured by nine sensors installed on the end wall 32 in the case of FIGS. 4B and 5A. Sensor 5 is placed at the center of the end wall 32 to measure the maximum of the measured temperature values.

Referring to FIG. 4B, even when the taper of the mold 30 is appropriate as shown in FIG. 4B, the measured value of the temperature according to the position of the measuring units 100 and 200 may be constant. However, the difference between the maximum value and the minimum value of the measured temperature value is only 30 ° C (140 ° C-110 ° C). This difference is judged to be appropriate as a normal difference in the mold 30 with a proper taper.

However, in the case of FIG. 5A, the temperature drop in the part where the solidification shell 81 is far from the mold 30 is large, and the minimum value has reached 80 degreeC level. As a result, the difference between the maximum value and the minimum value reaches 60 ° C (140 ° C-80 ° C). This is outside the normal deviation, and in this case, it is determined that the taper of the mold 30 is insufficient.

7 is a graph showing the correlation between the casting speed and the mold 30 temperature to determine the appropriate taper according to the casting speed.

Referring to this figure, as the casting speed increases, the temperature of the mold 30 increases linearly. Accordingly, the formula 30 temperature = 35.714 x casting speed + 64.905 can be derived.

According to this relationship, the mold 30 temperature has a correlation with the casting speed, but there are some variations due to powder, cooling water for the mold 30, oscillation for the mold 30, and the like. The temperature due to such fluctuations is in the grayed out region in the graph.

In some cases, abnormally low temperature values may be detected, as indicated by red dots. In this case, it may be determined that the taper of the mold 30 is inappropriate.

Referring now to Figure 8 will be described a method for determining the taper of the continuous casting associated with another embodiment of the present invention.

8 and 4B, the temperature of the set portion of the mold 30 is measured through the measuring units 100 and 200 (S1). The determination unit 300 compares the temperature deviation between the maximum value and the minimum value and the reference temperature value among the measured temperature values (S2). From this comparison, the determination unit 300 determines the degree of taper.

It is determined whether the measured temperature deviation and the reference temperature value are within the first deviation in preparation for the case where the taper is appropriate (S3). Here, the first deviation may be about 60 ℃.

If the taper is outside the first deviation range, the taper is adjusted by turning the end wall 32 of the mold 30 (S4). After the taper adjustment, the work can be checked again to see if the taper is within the first deviation.

If the taper is within the first deviation range, it may be determined whether the taper is within the second deviation (S5). Here, the second deviation is a range smaller than the first deviation, the second deviation may be about 30 ℃, which is for further investigation for more precise taper adjustment.

If the taper is within the second deviation range, the taper adjustment may be sufficient. If the taper is out of the second deviation range (although within the first deviation range), the taper can be appropriately adjusted through powder, oscillation, cooling control, or the like.

In this process, the determination result of whether the taper is appropriate may be notified to allow the operator to manually adjust the taper. Alternatively, the taper may be automatically adjusted by driving a driving device for pivotally driving the end wall 32.

The taper determination device and method of the continuous casting mold as described above is not limited to the configuration and operation of the embodiments described above. The above embodiments may be configured such that various modifications may be made by selectively combining all or part of the embodiments.

10: ladle 15: shroud nozzle
20: tundish 25: immersion nozzle
30: mold 31: sheet wall
32: single wall 40: mold oscillator
50: powder feeder 51: powder layer
52: liquid fluidized bed 53: lubricating layer
60: support roll 65: spray
70: pinch roll 80: strand
81: solidified shell 82: unsolidified molten steel
83: tip 85: solidification completion point
87: oscillation mark 88: bulging area
100, 200: measuring unit 110, 120, 130, 140, 150: sensor
210,220,230,240,250: sensor 300: judgment unit

Claims

A mold having two pairs of walls defining an interior cavity, the mold being configured to solidify and discharge a portion of the incoming molten steel;
A measurement having a plurality of sensors installed at corners where adjacent walls of the mold meet and arranged in a horizontal row from one of the two adjacent walls to the other to measure the temperature of the mold changed by the molten steel unit; And
And a determination unit that determines whether the taper of the walls of the mold is appropriate based on the temperature value measured by the measuring unit.

delete

The method of claim 1,
The taper discrimination apparatus of the continuous casting mold, wherein the sensors of the measuring unit are disposed along the circumferential direction of the mold.

delete

The method of claim 1,
And the judging unit compares the measured temperature value with a reference value to determine whether the taper is appropriate.

The method of claim 1,
And the determining unit compares a reference value of the temperature of the mold with the casting speed and the measured temperature value to determine whether the taper is appropriate.

Measuring a temperature pattern in the circumferential direction of the mold to which the molten steel is solidified through a sensor disposed at a corner portion where adjacent walls of the mold meet and arranged in a horizontal row from one of the two adjacent walls to the other;
Comparing the measured temperature pattern with a reference pattern; And
Determining whether the taper of the walls of the mold is appropriate from the comparison result.

delete

The method of claim 7, wherein
And the temperature pattern is a temperature distribution measured by a plurality of sensors.

The method of claim 7, wherein
And informing the determination result of the degree of the taper or adjusting the taper according to the determination result.