KR101224970B1 - Device for predicting surface crack of products in continuous casting process and method therefor - Google Patents

Abstract

The present invention relates to an apparatus and method for predicting surface cracks of a product in a playing process for indirectly predicting the occurrence of surface cracks of a final rolled product such as a coil produced through a playing process. The operation variable value is obtained by multiplying a memory in which operation data is stored, a circumferential speed detecting unit for detecting a casting speed of a casting cast through a mold, and a casting speed and a height of the tundish of the casting cast detected through the circumferential speed detecting unit. And a control unit for predicting the degree of surface crack generation using the obtained operation variable value and variably controlling the height or casting speed of the tundish according to the prediction result.

Description

DEVICE FOR PREDICTING SURFACE CRACK OF PRODUCTS IN CONTINUOUS CASTING PROCESS AND METHOD THEREFOR}

The present invention relates to the prediction of surface crack occurrence, and more particularly, to an apparatus and method for predicting surface cracks of a product in a reproducing process for predicting the degree of surface cracking of a final rolled product such as a coil produced through a reproducing 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 (Tundish) and then supplied to a continuous casting machine mold.

The continuous casting machine includes a ladle for storing molten steel, a casting mold for forming a tundish and a molten steel that is guided in the tundish first to form a cast slab having a predetermined shape, and a casting member connected to the mold, A plurality of pinch rolls and the like. The molten steel introduced from the ladle and the tundish is formed into a cast slab having a predetermined width, thickness and shape in the mold and is transported through the pinch roll. The slab transported through the pinch roll is cut by a cutter to have a predetermined shape Slabs, blooms, billets, and the like.

Thin slab produced in the playing process is thin as 40 to 100mm in thickness, can be omitted in the hot rolling process rough rolling process is mainly applied to the process omission and simplification.

An object of the present invention relates to an apparatus and a method for predicting the surface crack of a product in the playing process that can predict the degree of surface crack generation of the final rolled product using the casting speed and the tundish height information in the playing process.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above.

Surface crack prediction device of the present invention for realizing the above object is a memory for storing the operation data for the height of the tundish and various set values; A circumferential speed detection unit for detecting a casting speed of the casting cast through the mold; And multiplying the casting speed of the playing piece detected by the circumferential speed detecting unit with the height of the tundish to obtain an operation variable value, using the obtained operation variable value to predict a degree of surface crack generation, and according to the prediction result, a tundish It may include; a control unit for controlling the height or the casting speed of the variable.

The control unit may obtain a surface crack index by calculating the operation parameter value and a predetermined relational constant, and predict the occurrence of surface cracks using the surface crack index. The controller may increase the casting speed or increase the height of the tundish when the surface crack index exceeds a predetermined reference value.

Surface crack prediction method of the present invention for realizing the above object, detecting the casting speed of the cast pieces cast through the mold; Checking the height of the tundish positioned on the mold; Acquiring the operation variable value VcTd by multiplying the detected casting speed by the height of the tundish; And calculating a surface crack index ( SCI ) by calculating the operation variable value obtained above and a predetermined relational constant, and predicting the occurrence of surface cracks by the surface crack index.

The relation constant may be a value derived by a correlation between the operation variable value and the actual degree of surface crack occurrence.

When the surface crack index calculated above exceeds a predetermined reference value, the method may further include increasing the casting speed or controlling the height of the tundish to increase.

According to the present invention as described above, it is possible to predict the occurrence of product surface cracks by using the casting speed and the height of the tundish in the thin slab process. In addition, there is an advantage to calculate the depth of the appropriate immersion nozzle for each circumference that can reduce the surface defects by using the surface crack index.

1 is a conceptual diagram showing a continuous casting machine according to an embodiment of the present invention mainly on the flow of molten steel.
2 illustrates a surface crack prediction apparatus according to an embodiment of the present invention.
3 is a view showing the immersion depth of the immersion nozzle according to the height of the tundish.
4 is a view showing a mold for thin slabs and surface cracks.
5 is a diagram showing a center crack and an edge crack of the final product, respectively.
6 is a flowchart illustrating a surface crack prediction process according to an embodiment of the present invention.
7 and 8 are graphs showing the correlation between the operation variable value and the surface crack index according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like elements in the figures are denoted by the same reference numerals wherever possible. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

1 is a conceptual diagram showing a continuous casting machine according to an embodiment of the present invention mainly on the flow of molten steel.

Continuous casting is a casting process in which a molten metal is continuously cast into a bottomless mold while continuously drawing a steel ingot or steel ingot. Continuous casting is used to manufacture slabs, blooms and billets, which are mainly rolled materials, and long products of simple cross-section such as square, rectangle, and circle.

The type of continuous casting machine is classified into vertical type and vertical curved type. In Fig. 1, a vertical bending type is illustrated.

Referring to FIG. 1, the continuous casting machine may include a ladle 10, a tundish 20, a mold 30, secondary cooling tables 60 and 65, a pinch roll 70, and a cutter 90. have.

The tundish 20 is a container that receives the molten metal from the ladle 10 and supplies the molten metal to the mold 30. 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 due to 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 is formed such that a solidified shell or a solidified shell 81 is formed so as to maintain the shape of the casting pluck pulled out from the mold 30 and to prevent the molten metal from being hardly outflowed from flowing out. . The water-cooled 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. Lubricant is used to reduce friction between the mold 30 and the solidification shell 81 and prevent burning during oscillation. 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 and the lubrication of the mold 30 and the solidification shell 81 as well as the prevention of oxidation and oxidation of molten metal in the mold 30, It also functions to absorb the emerging nonmetallic inclusions. 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. The solidification of the cast steel is mostly made by the secondary cooling.

The drawing device adopts a multidrive method using a pair of pinch rolls 70 and the like so as to pull out the cast pieces 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 continuous casting machine configured as described above allows the molten steel M accommodated in the ladle 10 to flow into the tundish 20. For this flow, the ladle 10 is provided with a shroud nozzle 15 extending toward the tundish 20. The shroud nozzle 15 extends into the molten steel in the tundish 20 so that the molten steel M is not exposed to the air to be oxidized and nitrided.

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. By the way that the periphery is first solidified, the back portion along the casting direction of the casting cast piece 80 forms a shape in which the non-solidified molten steel 82 is wrapped in the solidified shell 81.

As the pinch roll 70 (FIG. 1) pulls the tip portion 83 of the completely cast solid cast piece 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 non-solidified molten steel 82 in the playing cast 80 to gradually decrease. When the cast steel 80 reaches one point 85, the cast steel 80 is filled with the solidification shell 81 of the entire thickness. The solidified cast piece 80 is cut to a certain size at the cutting point 91 is divided into slabs (P) such as slabs.

The thin slabs produced through the continuous casting machine are rolled and then produced as hot rolled coils or plates. The thickness of the thin slabs produced through the playing process may be about 40 to 100 mm, and the thickness of the coils produced through the rolling process may be about 1 to 20 mm.

2 is a view showing a surface crack prediction apparatus according to an embodiment of the present invention, the prediction apparatus 100 is a memory 110, a peripheral speed detection unit 120, a height adjusting unit 130, an input unit 140, a control unit ( 150 and the display unit 160.

The memory 110 may store operation data of at least one of the current height of the tundish 20 and the casting speed during continuous casting, the width of the cast steel, the product thickness of the final product after rolling, and various setting values. . The final product may be a hot rolled coil or a thick plate, but in the present invention will be described with respect to the coil.

The circumferential speed detecting unit 120 detects a casting velocity of the cast piece 80 cast through the mold 30 in real time through the rotation speed of the pinch roll 70. Here, the casting speed may be detected in real time through the circumferential speed detecting unit 120, but may be provided from a system for controlling the speed of the pinch roll 70.

The height adjusting unit 130 may be configured as a hydraulic cylinder operated according to a control signal to adjust the height by moving the tundish 20 up and down. The height of the tundish 20 is indirectly checking the immersion depth of the immersion nozzle 25 through the height of the tundish 20 at the interval between the top surface of the mold 30 and the bottom surface of the tundish 20. It is possible.

The input unit 140 is configured to receive the necessary operation data such as the adjustment command of the tundish 20 or the width of the performance casting piece during continuous casting, the product thickness for the final product after rolling, and various setting values from the outside.

The controller 150 multiplies the casting speed of the performance casting piece 80 detected by the main speed detection unit 120 with the current height of the tundish 20 set in the memory 110 to obtain a value of the operation variable, and obtains the operation variable obtained. The value of the surface crack generation is predicted using the value, and the height or casting speed of the tundish 20 is variably controlled according to the predicted result. In addition, the controller 150 may obtain a surface crack index by calculating the operation parameter value and a predetermined relational constant, and predict the occurrence of surface cracks using the surface crack index. In the above, the relation constant is a value derived by the correlation between the operation variable value and the actual surface crack occurrence degree.

Here, the controller 150 may obtain the casting speed through the peripheral speed detector 120, but may be input by the user through the input unit 140. In addition, the height of the tundish 20 may also be input by the user through the input unit 140.

In addition, the controller 150 compares the calculated surface crack index and the set reference value, and if the surface crack index exceeds the reference value, the pinch roll 70 is controlled to increase the casting speed or the height adjusting unit 130. By controlling the control so that the height of the tundish 20 is increased. Here, when the height of the tundish 20 is increased, the depth of deposition of the immersion nozzle 25 is lowered as shown in FIG. 3. That is, if the height of the tundish 20 is known, the immersion depth of the immersion nozzle 25 may be indirectly confirmed, for example, as shown in Table 1 below.

The display unit 160 may display the current height or casting speed of the tundish 20, the obtained operation variable value, the surface crack index, and the predicted degree of surface crack generation in text or graph under the control of the controller 150.

Casting speed Height of tundish Immersion Depth of Immersion Nozzle One 3.5 m / min 63 mm 172 mm 2 4m / min 55 mm 180 mm 3 4.5 m / min 49 mm 186 mm 4 5 m / min 44 mm 191 mm 5 5.5 m / min 40mm 195 mm

In Table 1, the height of the tundish means the maximum height of the tundish at each casting speed, which means that the height of the tundish at the corresponding casting speed should not exceed the maximum height. The immersion depth of the immersion nozzle is a distance from the hot water surface to the upper end of the discharge port 26 of the immersion nozzle 25 as a value converted using the height of the tundish. As the height of the tundish 20 increases, the immersion depth of the immersion nozzle 25 becomes shallow, and as the height of the tundish 20 decreases, the immersion depth of the immersion nozzle 25 deepens.

As such, the prediction apparatus 100 may indirectly predict the degree of surface crack generation of the final product by calculating the operation variable value in real time using the casting speed and the height information of the tundish 20.

In general, in order to cast the thin slab at a high speed, a funnel-type mold 30 is used as shown in FIG. 4, and the solidification non-uniformity in the mold is greater than that of a general player due to this process feature. In particular, because of the funnel-shaped geometric characteristics, surface cracks may occur at the center portion (A) and the edge portion (B) of the cast steel, which is the center crack (A) and edges on the surface of the hot rolled coil as shown in FIG. It can develop into cracks (B).

In order to increase the productivity of one tundish 20 and the immersion nozzle (25) to perform a long cast, the immersion of the immersion nozzle (25) occurs during casting is limited by the number of years. In order to overcome the limitation of the number of soft water in accordance with the melted hand of the immersion nozzle 25, the depth of the immersion nozzle 25 is changed to alleviate the concentration of the melted hand of the local immersion nozzle 25. It is possible to increase the number of soft water by adjusting the immersion depth of the immersion nozzle (25), but the flow change in the mold occurs according to the height difference of the immersion nozzle (25), in particular, the thin casting that is characteristic of the thin slab playing process Under the conditions of thickness and high speed casting, the solidification unevenness in the mold is further enhanced, and the likelihood of cracking of the final product increases as shown in FIG. 5.

Therefore, the present invention intends to indirectly predict the degree of surface crack generation of the final product using the height of the tundish, that is, the depth information of the immersion nozzle and the casting speed.

6 is a flowchart illustrating a surface crack prediction process of a thin slab according to an embodiment of the present invention, with reference to the accompanying drawings.

First, the control unit 150 of the prediction device 100 detects a casting velocity (m / min) of the cast pieces cast through the mold 30 in real time through the rotation speed of the pinch roll 70. (S11). Here, the casting speed may be detected in real time through the circumferential speed detecting unit 120, but may be provided from a system for controlling the speed of the pinch roll 70.

In addition, the controller 150 checks current height information of the tundish 20 stored in the memory 110 (S12). The controller 150 adjusts the height by moving the tundish 20 up and down through the height adjusting unit 130 according to the input command, and at this time, the height information of the adjusted tundish 20 is adjusted to the memory 110. Will be stored in. In addition, the memory 110 stores information on the immersion depth of the immersion nozzle 25 corresponding to the height of the tundish 20, as shown in Table 1, so that the immersion nozzle 25 through the height of the tundish 20 It is also possible to indirectly check the immersion depth of the.

Subsequently, the controller 150 calculates the operation variable value VcHt by multiplying the casting speed of the performance casting piece detected by the main speed detection unit 120 with the current height of the tundish 20 stored in the memory 110 (S13). ). Here, the cast slab is a thin slab, for example, the thickness thereof may be 55mm, the width is 900 ~ 1560mm, the casting speed is about 3.5 ~ 5.5m / min.

The controller 150 obtains a surface crack index ( SCI ) by calculating the operation variable value obtained above and a preset relation constant (S14), and obtains a surface crack index (SCI), such as a coil. Predict the degree of surface crack generation of the final product (S15). Here, the controller 150 may obtain the surface crack index (SCI) by substituting the obtained operation variable value into Equation 1 below.

Equation 1

Here, VcHt is an operation variable value, and the first constant value and the second constant value are relational constants, which are determined by the correlation between them when fitting the operation variable value and the actual surface crack incidence (surface crack index). The derived value.

In Equation 1, the second constant value is greater than the first constant value. Here, the first constant value may be a value between 0 and 1, and the second constant value may be set to a value between 14 and 20.

In Equation 1, the first constant value and the second constant value may be different depending on the prediction part, that is, whether to predict the crack of the product center part or the crack of the edge part. For example, when predicting a crack in the center portion, the first constant value may be a value between 0 and 1, and the second constant value may be a value between 15 and 16. When predicting the crack of the edge portion, the first constant value may be a value between 0 and 1, and the second constant value may be a value between 18 and 19. Here, the constant values related to the edge crack prediction may be set to a value larger than the constant value related to the center crack prediction. The first and second constant values may vary depending on the quality of the actual product in operation.

Meanwhile, the surface crack index (SCI) may be an index obtained by calculating the width and product thickness of the cast slab on the surface crack scores classified according to the surface crack degree. Here, the surface crack score means, for example, a score evaluated by classifying the actual surface crack degree into an arbitrary grade. When the degree of surface cracking is classified into grades 1 to 5, it means that the surface crack score increases from one point to five points. When the surface crack score is divided into five grades, up to two grades may be sold as genuine products, but at three or more grades, there may be a problem in sales. However, in the present invention, since it is difficult to subdivide the degree of surface cracking by only five classifications, the surface crack index is subdivided by calculating the width of the cast slab and the thickness of the final product at the surface crack score. In this way, it is preferable to subdivide the surface crack index by calculating the width of the cast slab and the thickness of the coil in order to increase the discrimination of the surface crack grade. Surface crack index (SCI) can be exponentialized by the following equation (2).

Equation 2

7 and 8 are graphs showing the surface crack index according to the operation variable value, the operation variable value and the surface crack index (SCI) has a substantially linear relationship under the same conditions. FIG. 7 is a graph showing a relational formula used for the center crack prediction, and FIG. 8 is a graph showing a relational formula used for the edge crack prediction.

In Fig. 7, the correlation between the operation variable value X and the surface crack index Y is " Y = -0.0236 (first constant value) · X + 15.394 (second constant value) ". In FIG. 7, the dot is the actual surface crack occurrence index and the solid line is the predicted surface crack occurrence index according to the present invention, and it is shown that the actual and the predictive model are substantially in agreement. Here, the first constant value according to the correlation between the operation variable value and the surface crack index may be, for example, '0.0236', and the second constant value may be '15 .394 '. In conclusion, the predictive model accuracy (R ² ) was about 83%. That is, by knowing the value of the operation variable, the final surface crack index (SCI) can be calculated, and the surface crack index (SCI) can predict the degree of surface crack generation in the center of the product.

In the case of surface crack index (SCI), there is no problem at '10' or less (operation variable value is '225' or more), but if '10' or more, product sales may be a problem.

)인 '10'을 초과할 경우 소정의 경보수단을 통해 경보음을 출력함과 아울러 턴디쉬(20)의 높이가 증가되도록 높이조절부(130)를 제어하거나 핀치롤(70)을 통해 주조속도를 증가시킬 수도 있다(S16). 여기서, 주조속도는 생산량과 연동되는 것이라 주조속도를 고정시킨 상태에서 턴디쉬(20)의 높이를 조절하는 것이 크랙 방지에 더 유리할 수 있다. 조업 특성상 침지노즐(25)에서 지속적으로 용손이 일어나기 때문에 고정된 턴디쉬(20)의 높이(침지노즐(25) 침적 깊이)에서 장시간 생산을 할 수가 없기 때문에 표면크랙지수를 고려하여 일정한 범위내에서 턴디쉬(20)의 높이를 계속 가변시키면서 생산하는 것이 유리하다.As such, the controller 150 predicts the possibility of surface cracks in real time according to the casting speed and the height of the tundish 20 through the surface crack index (SCI), and displays the predicted result on the graph as shown in FIG. Display or predicted surface cracks

) When exceeding '10' outputs an alarm sound through a predetermined alarm means and controls the height adjusting unit 130 to increase the height of the tundish 20 or through the pinch roll 70 It may be increased (S16). Here, the casting speed is to be linked with the production amount, it may be more advantageous to prevent the crack to adjust the height of the tundish 20 in a fixed state of the casting speed. Due to the characteristics of the operation, the immersion nozzles are continuously generated in the immersion nozzle 25, so that the production cannot be performed for a long time at the height of the fixed tundish 20 (immersion nozzle 25 deposition depth). It is advantageous to produce while keeping the height of the tundish 20 variable.

In Fig. 8, the correlation between the operation variable value X and the surface crack index Y is " Y = -0.0398 (first constant value) · X + 18.528 (second constant value) ". Here, the first constant value according to the correlation between the operation variable value and the surface crack index may be, for example, '0.0398', and the second constant value may be '18 .528 '. In conclusion, the predictive model accuracy (R ² ) was about 76%. That is, by knowing the value of the operation variable, the final surface crack index (SCI) can be calculated, and the surface crack index (SCI) can predict the degree of surface crack occurrence of the product edge portion.

)인 '10'을 초과할 경우 소정의 경보수단을 통해 경보음을 출력함과 아울러 주조속도를 증가시키거나 또는 턴디쉬(20)의 높이가 증가되도록 제어할 수도 있다.In the case of surface crack index (SCI), there is no problem at '10' or less (operation variable value is '215' or more), but if '10' or more, product sales may be a problem. As such, the controller 150 predicts the possibility of surface crack generation in real time according to the casting speed and the height of the tundish 20 through the surface crack index (SCI), and displays the predicted result on the graph as shown in FIG. Display or predicted surface cracks

In case of exceeding '10', the alarm sound may be output through a predetermined alarm means, and the casting speed may be increased or the height of the tundish 20 may be increased.

)에 대응되는 조업변수값의 값이, 예를 들어 '225'와 '215'로 상이하다. 따라서, 제어부(150)는 제품의 중앙부와 에지부의 크랙 예측에 관계없이, 조업변수값의 값이 평균값인 '220' 이상이 되면 최종제품의 품질이 양호한 것으로 판단할 수 있다.In the above-described crack prediction in the center and edge of the product, the reference value of the surface crack index (

The value of the operation variable corresponding to) is different from, for example, '225' and '215'. Accordingly, the controller 150 may determine that the quality of the final product is good when the value of the operation variable is equal to or greater than '220', which is an average value, regardless of the crack prediction of the center part and the edge part of the product.

Thus, in the present invention, it is possible to predict the occurrence of the surface crack of the product by using the casting speed and the height of the tundish 20 in the thin slab process, and the appropriate immersion nozzle for each casting speed to reduce the defect by using the surface crack index (25). ) Can be calculated.

The surface crack prediction method as described above is not limited to the configuration and operation method 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 20: Tundish
21: Stopper 25: Immersion nozzle
30: mold 51: powder layer
60: support roll 65: spray
70: pinch roll 80: performance cast
81: solidified shell 82: unsolidified molten steel
83: tip 85: solidification completion point
90: cutting machine 91: cutting point
100: prediction device 110: memory
120: speed detection unit 130: height adjustment unit
140: input unit 150: control unit
160: display unit

Claims (8)

A memory in which operation data for the height of the tundish and various setting values are stored;
A circumferential speed detection unit for detecting a casting speed of the cast steel cast through the mold; And
Obtain the operation variable value by multiplying the casting speed of the playing piece detected by the circumferential speed detection unit with the height of the tundish, predicting the occurrence of surface cracks using the obtained operation variable value, and according to the prediction result Control unit for controlling the height or the casting speed of the; Surface crack prediction apparatus of the product in the playing process comprising a.
The method according to claim 1,
The control unit obtains a surface crack index by calculating the operation parameter value and a predetermined relational constant, and predicts the surface crack generation degree using the surface crack index, the surface crack prediction apparatus of the product.
The method according to claim 2,
The control unit predicts the surface crack of the product in the playing process to control the increase in the casting speed or the height of the tundish when the surface crack index exceeds the set reference value.
The method according to claim 2,
And said relationship constant is a value derived by a correlation between an operation variable value and an actual degree of surface crack occurrence.
Detecting a casting speed of the cast steel cast through the mold;
Checking the height of the tundish positioned on the mold;
Acquiring the operation variable value VcTd by multiplying the detected casting speed by the height of the tundish; And
Calculating the surface crack index ( SCI ) by calculating the operation variable value and the predetermined relational constant obtained in the above, and predicting the occurrence of the surface crack by the surface crack index; Way.
The method according to claim 5,
Wherein said relationship constant is a value derived by a correlation between an operation variable value and an actual degree of surface crack occurrence.
The method according to claim 5,
The surface crack index ( SCI ) is calculated by the following equation, the first constant value is a value between 0 and 1, the second constant value is a surface crack of the product in the playing process is set to a value between 14 and 20 Forecast method.
Equation

Where VcTd is the value of the operating variable.
The method according to claim 5,
If the surface crack index calculated above exceeds a predetermined reference value, the method of predicting the surface cracks of the product in the playing process further comprising the step of controlling the height of the tundish or the casting speed.

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