JP2020501913A - Continuous casting apparatus and method - Google Patents

Abstract

A continuous casting apparatus capable of preventing damage such as cracks in a slab while reducing pressure, and reducing a thickness difference of a slab so as to conform to a rolling allowance, and a control thereof. Provide a way. The continuous casting method of the present invention is a continuous casting method that is performed in a continuous casting apparatus in which a plurality of segments are continuously provided and a cast piece drawn from a mold is continuously cast. When the slab is drawn from the mold, setting the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment to the first roll gap difference and strongly reducing the slab; When the slab is not drawn from the mold, the roll gap difference between the input cylinder and the output cylinder of the Nth segment is set to a second roll gap difference smaller than the first roll gap difference. Variably rolling down the slab, wherein the second roll gap difference varies according to the distance between the end of the slab and the Nth segment. And wherein the Rukoto. [Selection diagram] Fig. 1

Description

  The present invention relates to a continuous casting apparatus and a continuous casting method, and more particularly, to a method that can prevent damage such as cracks in a slab while strongly reducing the slab thickness, and reduce the thickness of the slab so as to conform to the rolling allowance. The present invention relates to a continuous casting apparatus capable of reducing a difference and a control method thereof.

  One of the manufacturing techniques in the steel field is a continuous casting technique. Such a continuous casting technique has an advantage that continuous casting can be performed with a large cross section, and a slab that is several times larger than a normal casting machine can be produced.

  On the other hand, according to the continuous casting technique, since the size of the slab is large and the length is long, the weight of the slab is so heavy that it reaches several tens tons. Therefore, the weight and temperature of the slab affect the production environment of the slab, and there is a problem that such an influence causes an error in the production of the slab.

  Such a prior art can be easily understood with reference to Korean Patent Publication No. 2015-0073760 and Korean Patent Publication No. 2015-0073397.

Korean Published Patent Application No. 2015-0073760 Korean Patent Publication No. 2015-073397

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the prior art, and the present invention reduces the roll gap reduction amount according to the progress of the end portion of the slab while drawing the slab. And a method of controlling a continuous casting apparatus capable of preventing damages such as cracks of a slab while reducing the slab, and reducing a thickness difference of a slab to conform to a rolling allowance. It is to provide.

  The continuous casting method of the present invention is a continuous casting method in which a plurality of segments are continuously provided, and the continuous casting method is performed in a continuous casting apparatus that continuously casts a slab drawn from a mold. Is drawn, the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment is set to the first roll gap difference, and the slab is strongly reduced; Is not pulled out, the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment is set to a second roll gap difference smaller than the first roll gap difference, and the slab is cast. Variably rolling down, wherein the second roll gap difference varies according to the distance between the end of the slab and the Nth segment. To.

  The second roll gap difference varies in proportion to the distance between the end of the slab and the Nth segment.

  The step of strongly reducing the slab includes a step of setting a roll gap of a cylinder of the (N-1) th segment to a roll gap of the input side cylinder of the Nth segment.

  The step of strongly reducing the slab includes setting the roll gap of the cylinder of the (N + 1) th segment to the roll gap of the output side cylinder of the Nth segment.

  The step of variably rolling down the slab is a step of confirming the position of the end of the slab, and when the end of the slab advances beyond a reference length, the input side cylinder of the Nth segment and Reducing the roll gap difference between the output side cylinders based on a preset reduction amount of rolling reduction.

  The step of variably reducing the slab further includes the step of adjusting a reduction amount of the input side cylinder of the (N + 1) th segment based on a change amount of the reduction amount of the output side cylinder of the (N) th segment. It is characterized by the following.

  In addition, the present invention includes a plurality of segments including an input side cylinder and an output side cylinder, a segment portion where a slab is cast, an end position detection unit for detecting a position of an end of the slab, and the slab A controller that adjusts the pressure of the cylinder included in the plurality of segments so as to adjust the amount of reduction of the slab according to the position of the end of the slab. If not detected, the roll gap difference between the input cylinder and the output cylinder of the Nth segment is set to the first roll gap difference, and if the end of the slab is detected, the Nth segment is detected. The roll gap difference between the input side cylinder and the output side cylinder of the segment is set to a second roll gap difference smaller than the first roll gap difference.

The control unit, when the end of the slab advances more than the reference length, the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment based on a predetermined rolling reduction amount. It is characterized by lowering.

  The control unit may adjust the reduction amount of the input side cylinder of the (N + 1) th segment based on a change amount of the reduction amount of the output side cylinder of the (N) th segment.

  The above-mentioned means for solving the problems do not list all the features of the present invention. Various means for solving the problem of the present invention will be understood in more detail with reference to specific embodiments in the following detailed description.

  According to the present invention, by reducing the roll gap reduction amount according to the progress of the end portion of the slab while drawing the slab, it is possible to prevent damage to the slab, such as cracks, while strongly reducing the roll gap. effective.

  According to the present invention, by reducing the roll gap reduction according to the progress of the end portion of the slab while drawing the slab, it is possible to reduce the thickness difference of the slab to match the rolling allowance. There is an effect that can be done.

It is a figure showing one situation of the continuous casting device by one embodiment of the present invention. It is a figure showing other states of the continuous casting device by one embodiment of the present invention. It is a perspective view which shows an example of the segment of the continuous casting apparatus of FIG. FIG. 4 is a cut front view showing an example of the segment of FIG. 3. FIG. 1 is a block diagram illustrating a configuration of a continuous casting apparatus according to an embodiment of the present invention. It is a figure for explaining the segment controlled differently according to the position of the end of the slab in the continuous casting device by one embodiment of the present invention. It is a figure which compares the shape of the slab controlled differently according to the position of the end of a slab. 5 is a flowchart illustrating a continuous casting method according to an embodiment of the present invention.

  Hereinafter, a preferred embodiment of the present invention will be described. However, the embodiments of the present invention can be modified into some other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those having average knowledge in the art.

  In addition, in the entire specification, “including” a certain component does not exclude another component and may further include another component unless otherwise specified. means.

  FIG. 1 is a diagram showing one state of a continuous casting apparatus according to one embodiment of the present invention.

  The continuous casting will be described with reference to the example shown in FIG. The molten steel having undergone the refining process is poured into a tundish 10 from a ladle (not shown), and the molten steel temporarily stored in the tundish 10 is supplied to a mold 20.

  The molten steel is primarily cooled in a mold 20 and subsequently solidified through a secondary cooling in a strand line 21 below the mold, so that slabs such as billets, blooms, slabs, and the like are formed. S is produced continuously.

  On the other hand, molten steel M (Molten steel) discharged through the mold 20 is subjected to primary cooling in the mold 20, and the surface is slightly solidified, and the continuous segments (Segment) 1 to n + 1 provided in the continuous casting equipment 100. And then pressed.

  That is, each segment 110 has an upper roller and a lower roller, and the segment 110 includes a cylinder that provides pressure to the upper roller and the lower roller. As in the example shown in the figures, each segment has an input cylinder 111 and an output cylinder 112, which provide pressure to the input and output upper and lower rollers, respectively.

  On the other hand, in order to improve the internal quality of the central portion in the continuous casting process, the slab S is lowered by using the above-described roller in the segment corresponding to the final stage of solidification of the slab S. For example, the segment corresponding to the last stage of solidification of the slab is cast by strongly pressing the slab S inside and outside 20 mm, thereby smoothing the solidification of the slab S and improving the quality of the slab such as flatness. Can be improved.

  For example, assuming that the point of the segment n corresponds to the final stage of solidification of the slab S, the segment n casts the slab S by strongly pressing it in and out of 20 mm, and the rolling force in the segment n is smaller than the rolling force in the segment n-1. Is also set higher.

  On the other hand, when the unsolidified portion of the slab S is strongly reduced so as to have a roll gap of 20 mm or more, a crack may be generated in the unsolidified portion of the slab S. It is important to prevent

  Therefore, the continuous casting apparatus according to the present invention prevents the slab S from cracking by adjusting the rolling force in accordance with the progress of the slab S so that the slab can be stably and strongly reduced. be able to. In addition, by gradually adjusting the rolling force, by minimizing the thickness difference between the leading end and the trailing end of the slab, to meet the rolling tolerance standard value required in the subsequent process. can do.

  FIG. 2 is a diagram showing another state of the continuous casting apparatus according to one embodiment of the present invention, and shows an example in which the end Send of the slab S is further advanced from the one state shown in FIG.

  When the end Send of the slab S is derived in this way, that is, when the slab is not pulled out from the mold, the end Send of the slab S is likely to be broken by continuously and strongly reducing the pressure in the segment n. May occur.

  Therefore, the continuous casting apparatus according to one embodiment of the present invention can adjust the pressure of the cylinder of the segment so as to adjust the amount of reduction of the segment according to the position of the end Send of the slab.

  FIG. 3 is a perspective view showing an example of a segment of the continuous casting apparatus of FIG.

  As shown in FIG. 3, the segment 110 includes an upper roller 32 and a lower roller 34. The upper roller 32 and the lower roller 34 can be composed of a plurality of rollers.

  Molten steel is cast and rolled between the upper roller 32 and the lower roller 34 of the segment 110 to produce a slab.

  Upper and lower frames 36 and 38 on which the upper roller 32 and the lower roller 34 are mounted are provided with a pressing cylinder 40, and the pressing cylinder 40 can apply pressure to the upper roller 32 and the lower roller 34.

  In the example shown in the drawing, a total of four cylinders are provided, one on each of the left and right sides of the input side and the output side of the segment. This is an example, and the number of cylinders is not limited to the embodiment. The settings can be changed accordingly.

  The cylinder 40 is fixed by side boxes 42 and 44 on the side of the frame, and can be linked via a tie rod 46.

  The upper roller 32 and the lower roller 34 are assembled by girders 48, 50 between the frames 36, 38.

  FIG. 4 is a cut front view showing an example of the segment of FIG.

  As shown in FIG. 4, the segment 400 includes an input cylinder 440 and an output cylinder 430 provided between the upper and lower frames 436 and 438, and a drive roll 420 provided between the input cylinder 440 and the output cylinder 430. ,including.

  The drive roll 420 is merely for transferring the slab, and is different from the upper and lower rollers 432 and 434 for lowering the slab by the cylinders 430 and 440. The upper and lower portions of the cylinder 440 are connected via a tie rod 446, and the upper and lower rollers 432 and 434 apply pressure to the slab according to the pressure of the cylinder 440.

  On the other hand, as described above, the continuous casting apparatus according to the embodiment of the present invention adjusts the segment pressure in accordance with the position of the end of the slab. Hereinafter, this will be described in more detail with reference to FIGS.

  FIG. 5 is a block diagram illustrating the configuration of the continuous casting apparatus according to one embodiment of the present invention.

  As shown in FIG. 5, the continuous casting device 200 includes a segment part (not shown), a terminal position detection part 210, and a control part 220.

  The segment portion includes a plurality of segments for casting a slab. As described above, each segment includes an input side cylinder and an output side cylinder.

  The end position detection unit 210 can detect the position of the end Send (shown in FIG. 2) of the slab.

  Various techniques for detecting the end of the slab can be applied to the end position detection unit 210. As an example, the end of the slab can be detected by using the image detecting means, and as another example, the end of the slab can be detected by using the heat sensing means. In addition, various means can be applied, and in the present invention, the end position detecting unit 210 is not limited to a specific technical means.

  The control unit 220 can control the cylinder of the segment.

  The control unit 220 can adjust the pressure of the cylinder included in the plurality of segments so as to adjust the reduction amount of the slab according to the position of the end of the slab.

  As an example, when the end of the slab is not detected, that is, when the slab is continuously pulled out of the mold, the control unit 220 determines the roll gap between the input cylinder and the output cylinder of the Nth segment. The difference can be set to the first roll gap difference. On the other hand, when the end of the slab is detected, that is, when the slab is not pulled out of the mold, the control unit 220 determines the roll gap difference between the input cylinder and the output cylinder of the Nth segment. The second roll gap difference can be set smaller than the first roll gap difference.

  Here, the second roll gap difference can be changed according to the distance between the end of the slab and the Nth segment. As an example, the second roll gap difference can be changed to be proportional to the distance between the end of the slab and the Nth segment.

  That is, when the slab is continuously withdrawn from the mold, the control unit 220 controls the N-th segment corresponding to the last stage of solidification of the slab S to be strongly reduced with a strong pressure, When the end of the slab is generated without being pulled out as described above, the pressure of the Nth segment can be controlled to be gradually reduced according to the position of the end of the slab.

  The control unit 220 lowers the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment based on a preset reduction amount when the end of the slab advances beyond the reference length. be able to.

  For example, the control unit 220 periodically monitors the distance that the end of the slab moves, so that when the end of the slab moves by the reference length Li, the reduction in the Nth segment is strongly reduced. The roll gap of the Nth segment can be controlled by calculating the target roll gap set value (the reduction amount (PV) -ΔRi) for reducing the amount by the fixed reduction amount ΔRi.

  The control unit 220 can adjust the reduction amount of the input side cylinder of the (N + 1) th segment based on the change amount of the reduction amount of the output side cylinder of the (N) th segment.

  The control unit 220 is realized by a control device such as a PLC (Programmable Logic Controller), for example, but is not necessarily limited thereto.

  FIG. 6 is a diagram for explaining segments that are controlled differently according to the position of the end of the slab in the continuous casting apparatus according to one embodiment of the present invention.

  FIG. 6A shows an example in which the ends of the slab are not yet formed, and FIG. 6B shows an example in which the ends of the slab are formed and the amount of reduction is adjusted accordingly.

  First, in the case of FIG. 6 (a), it can be seen that strong reduction is performed in the segment n corresponding to an unsolidified portion where the molten steel 610 in the slab is not sufficiently solidified. Therefore, the height difference of the slab between the previous segment n-1 and the subsequent segment n + 1 is set to d1. By setting the roll gap difference between the input side cylinder and the output side cylinder of the segment n to be equal to or more than a certain roll gap difference, it is possible to realize the difference in the amount of reduction in these rolls.

  On the other hand, in the case of FIG. 6B, it can be seen that the amount of reduction of the segment n is reduced to d2 as the end of the slab advances. This can reduce the rolling reduction by reducing the roll gap difference between the input side cylinder and the output side cylinder of the segment n.

  On the other hand, the reduction amount of the input side cylinder of the segment n + 1 can be changed based on the change amount of the reduction amount of the output side cylinder of the segment n.

  FIG. 7 is a diagram comparing the shapes of the slabs that are controlled differently according to the position of the end of the slab.

  FIG. 7A shows an example in which the ends of the slab are not yet formed, and FIG. 7B shows an example in which the ends of the slab are formed and the amount of reduction is adjusted accordingly.

  In the case of FIG. 7A, the slab is drawn out of the mold, and the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment is set to the first roll gap difference. This is the case where the slab is strongly reduced.

  In the case of FIG. 7B, the cast slab is not pulled out from the mold, and the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment is smaller than the first roll gap difference. This is a case where the cast slab is variably reduced by setting a difference between two roll gaps. As shown in the drawing, the second roll gap difference varies depending on the distance between the end of the slab and the Nth segment.

  As the end of the slab moves by the distance X1, the section in which the reduction amount of the slab fluctuates also corresponds to X1.

  That is, in FIG. 7A, the roll gap Rt is formed only by the n-th segment, whereas in FIG. 7B, the roll gap by the n-th segment is only R1, and the end of the cast slab is formed. It can be seen that the rolling reduction R2 is set by the section X1 in which the rolling reduction is gradually reduced based on the moving distance of.

  As a result, the end of the slab passes through a certain point, and accordingly, the amount of reduction of the n-th segment gradually decreases based on the movement of the end of the slab. This prevents cracks at the ends of the slab, and the amount of change in the slab is set within a certain level, so that the rolling permission rate can be satisfied.

  FIG. 8 is a flowchart illustrating a continuous casting method according to an embodiment of the present invention.

  Since the continuous casting method shown in FIG. 8 is performed in the continuous casting apparatus described with reference to FIGS. 1 to 7, it can be easily understood with reference to the contents described above with reference to FIGS. .

  When the slab is drawn from the mold (S810, No), the continuous casting apparatus sets the roll gap difference between the input side cylinder and the output side cylinder of the N-th segment to the first roll gap difference. Can be strongly reduced.

  On the other hand, when the casting in the mold is completed and the slab is not drawn from the mold (S810, Yes), the continuous casting apparatus determines the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment by the first gap. By setting the second roll gap difference smaller than the roll gap difference, the slab can be variably reduced. Here, the second roll gap difference can be changed according to the distance between the end of the slab and the Nth segment.

  Specifically, the continuous casting apparatus can calculate the position of the end portion of the slab and track the position (S820).

  When the position of the end portion of the slab does not reach P1 set in advance, the continuous casting apparatus can perform the same strong pressure reduction as when the slab is drawn.

  As an example, the continuous casting apparatus can set the roll gap of the cylinder of the (N-1) th segment to the roll gap of the input side cylinder of the Nth segment. Alternatively, the continuous casting apparatus may set the roll gap of the cylinder of the (N + 1) th segment to the roll gap of the output side cylinder of the Nth segment.

  On the other hand, when the position of the slab end portion is already set and reaches P1, the pressure can be reduced variably (S840 to S880).

  More specifically, the continuous casting apparatus calculates the currently proceeding length of the terminal portion (S840), and reduces the amount of reduction by a certain amount every time the currently proceeding length corresponds to the reference length (S850). It can be readjusted by reducing the amount (S860). In addition, the continuous casting device can control the roll gap of the segment based on the amount of reduction (S870).

  If the readjusted reduction amount corresponds to the final reduction amount (S880, Yes), the continuous casting device stops adjusting the reduction amount. On the other hand, when the readjusted rolling amount does not correspond to the final rolling amount (S880, No), the above-described process of reducing the rolling amount (S840 to S880) is repeatedly performed.

  Although the present invention has been described with reference to the embodiments and the drawings that are limited to specific matters such as specific components, the present invention is provided to help a more general understanding of the present invention. Therefore, the present invention is not limited to the above-described embodiment, and various modifications and variations can be made from such descriptions by those having ordinary knowledge in the technical field to which the present invention belongs.

  Therefore, the concept of the present invention should not be limited to the above-described embodiments, and is not limited to the claims described below, but is equally or equivalently modified to the appended claims. Can be said to belong to the scope of the idea of the present invention.

The pressing cylinder 40 is fixed by side boxes 42 and 44 on the side of the frame, and can be linked via a tie rod 46.

The drive roll 420 is merely for transferring the slab, and is different from the upper and lower rollers 432 and 434 for lowering the slab by the cylinders 430 and 440. Cylinder 430, 440, upper and lower portions are connected via a tie rod 446, the upper and lower rollers 432, 434 in response to the pressure in the cylinder 430, 440 will apply a pressure to the cast slab.

Claims (9)

A plurality of segments are continuously provided, a continuous casting method performed in a continuous casting apparatus that continuously casts a slab drawn from the mold,
When a slab is drawn from the mold, a step of setting the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment to the first roll gap difference and strongly reducing the slab,
When the slab is not pulled out from the mold, the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment is set to a second roll gap difference smaller than the first roll gap difference. Variably rolling down the slab with
The continuous casting method according to claim 1, wherein the second roll gap difference varies according to a distance between an end of the slab and the Nth segment. The second roll gap difference is:
The continuous casting method according to claim 1, wherein the distance varies in proportion to a distance between an end of the slab and the Nth segment. Strongly reducing the slab,
The method according to claim 1, further comprising: setting a roll gap of the cylinder of the (N−1) th segment to a roll gap of the input side cylinder of the (N) th segment. Strongly reducing the slab,
The method of claim 1, further comprising: setting a roll gap of a cylinder of an (N + 1) th segment to a roll gap of the output side cylinder of the Nth segment. Variably rolling down the slab,
Confirming the position of the end of the slab,
Lowering the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment based on a preset reduction amount when the end of the slab advances more than a reference length. The continuous casting method according to claim 1, comprising: Variably rolling down the slab,
The continuation according to claim 5, further comprising the step of adjusting a reduction amount of the input side cylinder of the (N + 1) th segment based on a change amount of the reduction amount of the output side cylinder of the (N) th segment. Casting method. Including a plurality of segments including the input side cylinder and the output side cylinder, a segment portion where a slab is cast,
An end position detection unit that detects the position of the end of the slab,
In accordance with the position of the end of the slab, to adjust the amount of reduction of the slab, including a control unit that adjusts the pressure of the cylinder included in the plurality of segments,
The control unit includes:
If the end of the slab is not detected, the roll gap difference between the input cylinder and the output cylinder of the Nth segment is set to the first roll gap difference,
When the end of the slab is detected, the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment is set to a second roll gap difference smaller than the first roll gap difference. A continuous casting apparatus characterized by the following. The control unit includes:
When the end of the slab advances more than a reference length, the roll gap difference between the input side cylinder and the output side cylinder of the Nth segment is reduced based on a preset reduction amount. The continuous casting apparatus according to claim 7, wherein The control unit includes:
9. The continuous casting apparatus according to claim 8, wherein the reduction amount of the input side cylinder of the (N + 1) th segment is adjusted based on a change amount of the reduction amount of the output side cylinder of the Nth segment.

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