KR20120032917A - Device for controlling cooling of strand and method therefor - Google Patents

Abstract

PURPOSE: A strand cooling control system and method are provided to periodically measure and control the surface temperature of strand in a continuous casting process and secure strand with uniform quality. CONSTITUTION: A strand cooling control system(100) comprises a temperature measuring unit(110), a spray amount regulating unit(130), and a control unit(170). The temperature measuring unit measures the surface temperature of the width of strand. The spray amount regulating unit controls the amount of cooling water sprayed to the central and edge portions of the strand. The control unit calculates the temperature difference between the central and edge portions of the strand based on the surface temperature measured by the temperature measuring unit and controls the amount of cooling water through the spray amount regulating unit in order to reduce the temperature difference when the calculated temperature difference exceeds a set reference temperature.

Description

Strand cooling control device and its method {DEVICE FOR CONTROLLING COOLING OF STRAND AND METHOD THEREFOR}

The present invention relates to strand cooling control, and more particularly, to a strand cooling controller and a method for controlling the cooling temperature of the strand to be maintained in a continuous casting process.

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

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 into a strand having a predetermined shape, and a strand formed from the mold connected to the mold. It includes a plurality of pinch rolls to move.

In other words, the molten steel tapping out of the ladle and the tundish is formed of a strand having a predetermined width, thickness, and shape in a mold and is transferred through a pinch roll, and the strand transferred through the pinch roll is cut by a cutter to have a predetermined shape. It is made of a slab (Slab) or a slab (Bloom), billet (Billet) and the like.

Cooling water spray is installed between the pinch rolls, the cooling water and air is injected into the strand through the spray to lower the temperature of the strand.

SUMMARY OF THE INVENTION An object of the present invention is to provide a strand cooling control apparatus and a method for controlling the surface temperature of strands in a continuous casting process to control the temperature variation in the width direction of the strands periodically.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular embodiments that are described. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, There will be.

Strand cooling control apparatus of the present invention for achieving the above object, the temperature measuring means for measuring the surface temperature in the width direction of the strand; An injection amount adjusting unit for adjusting the amount of cooling water of the spray means respectively sprayed to the center and the edge of the strand; And calculating a temperature deviation between the center portion and the edge portion of the strand based on the surface temperature of the strand measured by the temperature measuring means, and when the calculated temperature deviation exceeds a set reference temperature, the temperature in the width direction of the strand. And a control unit controlling the amount of cooling water through the injection amount adjusting unit to reduce the deviation.

Specifically, the spray means is composed of a plurality of nozzles for respectively spraying the coolant to the left edge portion, the center portion and the right edge portion in the width direction of the strand, the plurality of nozzles is characterized in that it is individually controlled by the injection amount adjusting unit do.

The control unit increases or decreases the amount of cooling water injected to the edge portion based on the central portion of the strand, and the control unit changes the amount of cooling water through the injection amount control unit when the temperature deviation of the strands measured by a plurality of temperature measuring means has the same pattern. It is characterized by controlling.

The plurality of temperature measuring means is characterized in that the temperature measuring means adjacent to each other.

Strand cooling control method of the present invention for realizing the above object, the first step of calculating the temperature deviation between the center portion and the edge portion of the strand based on the surface temperature measured in the width direction of the strand; A second step of comparing and determining whether the calculated temperature deviation exceeds a preset reference temperature; And a third step of controlling the amount of cooling water sprayed to the center portion or the edge portion in order to reduce the temperature deviation between the center portion and the edge portion of the strand when the temperature deviation calculated according to the determination result exceeds a reference temperature. Characterized in that.

Specifically, in the third step, when the calculated temperature deviation exceeds the reference temperature, increasing or decreasing the amount of cooling water injected into the edge portion based on the center of the strand, and before controlling the amount of cooling water in the third step, When the temperature deviation of the strands measured by the plurality of temperature measuring means have the same pattern, it characterized in that the variable amount of cooling water.

In the second step, the reference temperature is set in a range of 20 ° C to 50 ° C.

According to the present invention as described above, it is possible to produce a strand having a certain quality by controlling the surface temperature in the width direction of the strand, the cracks that may occur in the strand due to the rapid temperature change by maintaining the surface temperature of the strand constant There is an effect that can minimize (crack).

1 is a side view showing a continuous casting machine according to an embodiment of the present invention.
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.
3 is a view showing a strand cooling control apparatus according to an embodiment of the present invention.
4 is a view showing a detailed configuration of the spray means of FIG.
5 and 6 are views showing a typical injection amount of the coolant when the strand is wide or narrow.
7 is a flowchart illustrating a strand cooling control process according to an embodiment of the present invention.
8 and 9 are diagrams for explaining the variation and uniformity of the temperature in the width direction of the strand.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention. Like elements in the figures are denoted by the same reference numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a side view showing a continuous casting machine according 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.

A tundish 20 is a container for receiving molten metal from a ladle 10 and supplying molten metal to a mold 30. Ladle 10 is provided in a pair, alternately receives molten steel to supply to the tundish 20. In the tundish 20, the supply rate of the molten metal flowing into the mold 30 is controlled, the molten metal is distributed to each mold 30, the molten metal is stored, and the slag and the nonmetallic 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 has a pair of structurally opposed faces open to form a hollow portion for receiving molten steel. In the case of manufacturing a slab, the mold 30 includes 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 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 strands extracted from the mold 30 retain their shape and the molten metal, which is still less solidified, does not flow out. 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 strands 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 strands, 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 primarily cooled in the mold 30. The primary cooled molten steel is directly cooled by the spray means 65 for spraying water while maintaining the solidification angle by the support roll 60 not to be deformed. Strand coagulation 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 to pull out the strands 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 strands 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 nitrified. The case where molten steel M is exposed to air due to breakage of shroud nozzle 15 is referred to as open casting.

The molten steel M in the tundish 20 flows into the mold 30 by a submerged entry 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 forming 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. The uncondensed molten steel 82 is cooled by the spray means 65 for spraying the cooling water in the above movement process. 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 certain size at the cutting point 91 and divided into slabs P such as slabs.

3 is a view for explaining a strand cooling control device according to an embodiment of the present invention, the strand cooling control device 100 is a temperature measuring means 110 and spray means 150, the injection amount adjusting unit 130 and It is configured to include a control unit 170.

The temperature measuring means 110 (111, 115) measures the temperature in the width direction of the strand 80 discharged from the mold, respectively. Here, the temperature measuring means 110 is a sensor for measuring the temperature of each point of the strand 80 by scanning the width direction of the strand 80, the scanning method may be used a variety of known methods. Temperature measuring means 110 may be installed in a plurality at appropriate intervals between the cutter 90 from the rear end of the mold 30 to which the coolant is injected.

The injection amount adjusting unit 130 adjusts the amount of cooling water of the spray means 150 which is respectively sprayed to the center portion and the edge portion of the strand 80.

The spray means 150 includes a plurality of nozzles 151 to 155 arranged in a line in the width direction of the strand 80, and the plurality of nozzles spray a predetermined amount of cooling water in the width direction of the strand 80. Here, the plurality of nozzles may be three, as shown in Figure 4, the three nozzles are the left nozzle 151 for injecting the coolant to the left margin (margin) of the strand along the width direction of the strand 80, and the strand The center nozzle 153 for spraying the coolant to the center of the center, and the right nozzle 155 for spraying the coolant to the right margin of the strand (margin). The spray means 150 shown in FIG. 3 has the same components as the spray means 65 of FIG. 2 but with different reference numerals for convenience.

The spray means 150 configured as described above is provided at the upper and lower ends of the strand 80, respectively, and the nozzles at the upper end and the nozzles at the lower end are installed such that the installation position and the spraying angle thereof have arbitrary deviations from each other. The spray angle of each nozzle of the spray means 150 is set to about 110 degrees, and the spray angle of each nozzle is set to overlap each other with adjacent nozzles. Further, the spray angle of each nozzle is set to a constant spray angle regardless of the magnitude of the width of the strand 80.

The spray means 150 configured as described above sprays the coolant to the left edge portion, the center portion, and the right edge portion in the width direction of the strand 80, respectively, and the amount of spraying from each nozzle may vary depending on the control.

The controller 170 calculates a temperature deviation in the width direction of the strand 80 based on the surface temperature in the width direction of the strand 80 measured by the temperature measuring means 115, and the calculated temperature deviation is a memory. When the reference temperature set in 180 is exceeded, the injection amount of the coolant is controlled to reduce the temperature deviation in the width direction of the strand 80.

In addition, the control unit 170 has a pattern with respect to the width direction of the strand 80 when the temperature deviation with respect to the width direction of the strand 80 measured by the plurality of adjacent temperature measuring means 111 and 115 have the same pattern. It is possible to control the injection amount of the cooling water to reduce the temperature deviation. This means that the cooling water amount is not adjusted when the temperature deviation in the width direction of the strand 80 occurs temporarily at any one point, but this is only an embodiment.

When the controller 170 calculates the temperature deviation with respect to the width direction of the strand 80, the controller 170 compares and calculates the temperature deviations with respect to the 1/4 point, the 2/4 point, and the 3/4 point, respectively, in the width of the strand 80. It is preferable to adjust the injection amount of both margins based on the 2/4 point which is the center. For example, when the central portion has a higher temperature than both edges, the controller 170 controls the injection amount adjusting unit 130 to reduce the amount of cooling water injected to both edge portions, and when the central portion has a lower temperature than both edge portions. There is controlled the injection amount adjusting unit 130 to increase the amount of cooling water injected to both edges.

5 and 6 are views showing a typical injection amount of the coolant when the strand is wide or narrow.

When the strand 80 is wide as shown in FIG. 5, the amount of cooling water sprayed from the left nozzle 151, the center nozzle 153, and the right nozzle 155 is controlled to the same amount.

However, when the strand 80 is narrow as shown in FIG. 6, the amount of cooling water injected from the left and right nozzles 151 and 155 is controlled to be smaller than that of the central nozzle 153. When the amount of cooling water sprayed from the central nozzle 153 is 1, the amount of cooling water sprayed from the left and right nozzles 151 and 155 may be about 0.5 to about 0.9.

7 is a flowchart illustrating a strand cooling control process according to an exemplary embodiment of the present invention, with reference to the accompanying drawings.

First, the controller 170 controls the amount of cooling water sprayed from the central nozzle 153, the left nozzle 151, and the right nozzle 155 through the injection amount adjusting unit 130 as an initial set value (S1). Here, the amount of cooling water sprayed through the center nozzle 153, the left nozzle 151, and the right nozzle 155 may vary according to the width of the strand 80. For example, when the strand 80 is wide as shown in FIG. 5, the amount of cooling water sprayed from the center nozzle 153, the left nozzle 151, and the right nozzle 155 is the same, and the strand 80 is as shown in FIG. 6. When the width is narrow, the amount of cooling water sprayed from the left nozzle 151 and the right nozzle 155 may be less than the amount of cooling water spraying from the central nozzle 153.

Subsequently, at least one of the temperature measuring means 111 and 115 installed between the cutter 90 and the rear end of the mold 30 as shown in FIG. 3 measures the surface temperature in the width direction of the strand 80 at regular intervals. Then, the measured temperature is output to the controller 170 (S2). Here, the surface temperature of the scanned strand 80 may be different from the temperature of the margin and center as shown in FIG. 8. In Figure 8 the edge is approximately 50 to 100 degrees Celsius higher than the central portion.

The controller 170 calculates a temperature deviation between the center and the margin of the strand 80 based on the temperature data input from the temperature measuring means 115 (S3), and the calculated temperature deviation is It is determined whether the preset reference temperature is exceeded (S4). The surface temperature of the strand 80 scanned may be approximately 700 ° C. to 1100 ° C., and the set reference temperature may be set between 20 ° C. and 50 ° C. FIG. In an embodiment, the reference temperature may be about 30 ° C. in consideration of the measurement temperature error of the temperature measuring means 115. In addition, when calculating the temperature deviation between the center portion and the edge portion, the center portion may be approximately 2/4 point in the width of the strand 80, and the edge portion may be 1/4 and 3/4 point in the width of the strand 80. . If necessary, the temperature deviation of the center portion and the edge portion may be calculated using the temperature average value of each of the divided regions of the strand 80 divided into three sections.

When the temperature deviation between the center portion and the edge portion of the strand 80 exceeds the set reference temperature, the control unit 170 is the surface of the strand 80, the width direction of the input through the adjacent temperature measuring means 111 It is determined whether the temperature also shows the same pattern exceeding the reference temperature (S5). For example, when the reference temperature is 30 ° C, the temperature deviation between the center portion and the edge portion measured by the first temperature measuring means 111 is 41 ° C, and the center portion and the edge portion measured by the second temperature measuring means 115. When the temperature deviation between the two is 39 ° C., and both of them have a higher temperature at the edge than the central part, the strands 80 measured by the first temperature measuring means 111 and the second temperature measuring means 115 have the same temperature deviation pattern. It can be said that.

As described above, when the temperature deviation of the strand 80 measured by the at least one temperature measuring means 111 and 115 exceeds the set reference temperature, the controller 170 controls the strand through the control of the injection amount adjusting unit 130. The amount of cooling water injected to the edge of the (S6) is adjusted. For example, if the temperature at the center is higher than the edge, the amount of cooling water injected to the edge of the strand is reduced. If the temperature at the center is lower than the edge, the amount of cooling water is injected to the edge. Here, as shown in FIG. 3, the controller 170 uniformly controls the at least one spray means 150 provided between the plurality of temperature measuring means 111 and 115 through the injection amount adjusting unit 130. Segment control) or individually controlling the injection amount adjusting unit 130 to adjust the flow rate of the cooling water.

The controller 170 is cooled by the left nozzle 151, the center nozzle 153 and the right nozzle 155 by using the temperature deviation between the center and the edge measured by one temperature measuring means 110 You can also adjust the quantity immediately. However, since there may be a temporary error in temperature measurement, when the temperature deviation of the strands measured by at least two or more temperature measuring means 111 and 115 shows the same pattern, the left nozzle 151 and the right nozzle ( It is also possible to adjust the amount of cooling water sprayed from the 155 or the central nozzle 153. When adjusting the amount of cooling water, the amount of cooling water sprayed from the central nozzle 153 is preferably controlled to increase or decrease the amount of cooling water sprayed from the left and right nozzles 151 and 155 in a fixed amount.

As shown in FIG. 8, when the temperature deviation between the center and the edge of the strand is higher than the set reference temperature, the controller 170 controls the amount of cooling water injected from the left and right nozzles 151 and 155 through the injection amount adjusting unit 130. Increase more. Accordingly, as shown in FIG. 9, the temperature deviation between the center and the edge of the strand can be eliminated.

As described above, the present invention measures the temperature along the width direction of the strand 80 to adjust the amount of cooling water in a direction to reduce the temperature deviation between the center portion and the edge portion of the strand 80, thereby making it possible to uniformize the width in the width direction and control the solidification. Through there is an advantage that can improve the surface and internal quality of the strand (80).

The present invention has been described with reference to the preferred embodiments, and those skilled in the art to which the present invention pertains to the detailed description of the present invention and other forms of embodiments within the essential technical scope of the present invention. Could be. Here, the essential technical scope of the present invention is shown in the claims, and all differences within the equivalent range will be construed as being included in the present invention.

10: ladle 15: shroud nozzle
20: Tundish 25: Immersion Nozzle
30: mold 40: mold oscillator
50: powder feeder 51: powder layer
52: liquid fluidized bed 53: lubricating layer
60: support roll 65: spray means
70: pinch roll 80: strand
81: solidified shell 82: unsolidified molten steel
83: tip 85: solidification completion point
90: cutting machine 91: cutting point
100: strand cooling control device 110: temperature measuring means
130: injection amount control unit 150: spray means
151, 155: left and right nozzles 153: center nozzle
170: control unit 180: memory

Claims (10)

Temperature measuring means for measuring a surface temperature in the width direction of the strand;
An injection amount adjusting unit for adjusting the amount of cooling water of the spray means respectively sprayed to the center and the edge of the strand; And
The temperature deviation between the center portion and the edge portion of the strand is calculated based on the surface temperature of the strand measured by the temperature measuring means, and if the calculated temperature deviation exceeds the set reference temperature, the temperature in the width direction of the strand. And a control unit controlling the amount of cooling water through the injection amount adjusting unit to reduce the deviation.
The method according to claim 1,
The spray means is composed of a plurality of nozzles for respectively spraying coolant to the left edge portion, the center portion and the right edge portion in the width direction of the strand, the plurality of nozzles are individually controlled by the injection amount control unit.
The method according to claim 1,
The control unit is a strand cooling control device for increasing or decreasing the amount of cooling water injected to the edge portion relative to the center of the strand.
The method according to claim 1,
The controller is a strand cooling control device for variably controlling the amount of cooling water through the injection amount control unit when the temperature deviation of the strands measured by a plurality of temperature measuring means has the same pattern.
The method of claim 4,
The plurality of temperature measuring means is a strand cooling control device, characterized in that the adjacent temperature measuring means.
The method according to claim 1,
The reference temperature is strand cooling control device is set in the range of 20 ℃ to 50 ℃.
Calculating a temperature deviation between a center portion and an edge portion of the strand based on the surface temperature measured in the width direction of the strand;
A second step of comparing and determining whether the calculated temperature deviation exceeds a preset reference temperature; And
And a third step of controlling the amount of cooling water sprayed to the center portion or the edge portion to reduce the temperature deviation between the center portion and the edge portion of the strand when the temperature deviation calculated according to the determination result exceeds the reference temperature. Strand cooling control method.
The method according to claim 7,
The third step is a strand cooling control method for increasing or decreasing the amount of cooling water injected to the edge portion based on the center portion of the strand when the calculated temperature deviation exceeds the reference temperature.
The method according to claim 7,
Before controlling the amount of cooling water in the third step, if the temperature deviation of the strands measured by the plurality of temperature measuring means having the same pattern with each other, the strand cooling control method for varying the amount of cooling water.
The method according to claim 7,
In the second step, the reference temperature is strand cooling control method is set in the range of 20 ℃ to 50 ℃.

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