KR20150075571A

KR20150075571A - Apparatus for producing bar of continuous casting process

Info

Publication number: KR20150075571A
Application number: KR1020130163653A
Authority: KR
Inventors: 신민철; 황종연; 김성연
Original assignee: 주식회사 포스코
Priority date: 2013-12-26
Filing date: 2013-12-26
Publication date: 2015-07-06

Abstract

The present invention relates to a casting machine, a casting machine, a casting mill, a casting mill, a casting mill, and a casting mill, An end heating device for heating the edge of the casting,
And a control section for controlling the residence time of the casting from the exit of the casting machine to the entrance of the roughing mill to satisfy the following expression (1).

Equation (1)
Here, t is the residence time from the exit of the casting machine to the entrance of the roughing machine, and T is the lowest temperature (캜) of the exit surface of the casting machine and the surface of the billet at the entrance of the roughing mill.

Description

TECHNICAL FIELD [0001] The present invention relates to an apparatus for producing a rolled material in a continuous casting process,

The present invention relates to an apparatus for producing a rolled material in a continuous casting process, and more particularly, to a method of producing a rolled material in a continuous casting process that includes an end heating device between a castor and a roughing mill, &Lt; / RTI >

Continuous casting is a continuous casting method in which molten metal is continuously injected into a mold and continuously casted from the lower part of the casting machine to obtain casts such as billets, blooms, slabs and the like to be.

Such continuous casting can produce a large sized product simply and quickly at low cost.

The continuous casting process generally refers to a technique in which a twin roll thin plate casting process is a technique of continuously supplying molten steel between two rotating casting rolls and continuously producing thin plates of several mm thickness directly from the molten steel.

First, in a basic continuous casting process, the continuous casting process may include a casting machine, a rough rolling mill, a finishing mill, and a winder, and the cast produced in the casting machine is rolled to a final thickness through a rough rolling mill and a finishing mill, .

Typically, as shown in the dotted lines in FIG. 1 and FIG. 2, the cast steel produced in the casting machine is formed such that the temperature of both end portions of the cast steel is lower than the temperature of the central portion when there is no separate heating device in the castor. This is because heat transfer is formed from the central portion of the cast steel forming the high temperature toward both ends of the piece.

In the case of rolling a cast steel having such a temperature deviation in the width direction to produce a rolled material, various defects are generated at both ends of the cast steel, and the quality of the rolled material produced by the cast steel may be deteriorated.

As shown in FIG. 1, conventionally, in a continuous casting process, there is a technique for preventing defects that may occur at both ends of the cast steel by heating the temperature of both ends of the cast steel through heat transfer in the width direction at the central portion of the cast steel, It is necessary to secure a considerable distance (10 m or more) between the rolling mill and the rough rolling mill.

As shown in FIG. 2, in order to prevent defects that may occur due to a temperature deviation in the width direction of the casting in a conventional continuous casting process, production in the casting machine through secondary cooling control in the width direction inside the casting machine A technique has been used in which the temperature of the both end portions of the cast steel is set to be higher than the temperature of the central portion so as to prevent defects due to temperature drop at both ends.

However, in the case of this conventional technique, excessive temperature rise at both ends of the cast steel causes a new type of defect on the high temperature part formed at both ends, or the casting on the high temperature part is not completely solidified, There is a problem that a phenomenon may occur.

When the whale phenomenon occurs, the casting itself can not proceed and the casting must be forcedly stopped. In the case of seriousness, the casting segment may be stuck in the segment and connected to a large-scale accident.

In this way, if the defect rate of the rolled material generated in the process of producing the rolled material by the cast steel is increased, the productivity due to the stop of the operation is lowered, and the production cost of the rolled material due to the extension of the working time, There is an increasing problem.

The present invention is realized by recognizing at least any one of the requirements or problems generated in the conventional continuous casting process.

There is provided a rolling material production apparatus for a continuous casting process capable of reducing various defects that may be generated in rolling a cast steel by reducing a temperature deviation in a width direction generated in the cast steel, .

In accordance with one aspect of the present invention, there is provided a casting mill comprising: a casting machine for producing a cast steel; a roughing mill for intermediate rolling the cast steel produced in the casting machine to produce a rolled material; An end heating device disposed in a traveling path of the casting moving to the edge of the casting,

And a control section for controlling the residence time of the casting from the exit of the casting machine to the entrance of the roughing mill to satisfy the following expression (1).

Equation (1)

Here, t is the residence time from the exit of the casting machine to the entrance of the roughing machine, and T is the lowest temperature (캜) of the exit surface of the casting machine and the surface of the billet at the entrance of the roughing mill.

Preferably, the end heating apparatus may be provided with a plurality of heating apparatuses for heating upper side edges and lower side edges of the cast steel, respectively.

Preferably, the apparatus may further include a spray cooler disposed at a rear end of the rough rolling mill to adjust a cooling amount in the width direction of the rolled material produced in the rough rolling mill.

Preferably, the spray cooler includes an end spray cooler disposed at both side edges of the rolled material above and below the rolled material, for spraying a coolant to an edge of the rolled material, and a spray cooler disposed at a central portion of the rolled material, A central spray cooler for spraying the coolant and a cooler control unit for controlling the amount of coolant injected through the end portion spray cooler and the center portion spray cooler so as to control the amount of cooling of the end portion spray cooler and the center portion spray cooler .

According to an embodiment of the present invention as described above, the configuration includes the configuration of the end portion heating device that is disposed in the moving path of the casting which moves through the casting machine and moves to the rough rolling mill, By reducing the various defects that can occur during the production of rolled materials by the directional temperature deviation, it is possible to prevent the decrease in productivity due to the shutdown of the operation and to reduce the production cost of the rolled material due to the extension of the operating time, Can be reduced.

According to an embodiment of the present invention, the residence time of the casting from the exit side of the casting machine to the entrance of the rough rolling mill is controlled to increase the section reduction ratio (RA) of the casting to increase the ductility of the casting, It is possible to prevent defects that may occur during rolling with the rolled material, thereby minimizing the interruption of operation and improving the process efficiency.

According to one embodiment of the present invention, the configuration of the spray cooler for adjusting the cooling amount in the width direction of the rolled material at the rear end of the rough rolling mill is included so that the widthwise temperature unevenness locally raised by the end heating device is controlled, It is possible to additionally prevent defects during rolling by the finishing mill after the rolling step by the rolling mill.

Fig. 1 and Fig. 2 are conceptual diagrams showing a method of solving a temperature variation in the width direction of a cast steel in a conventional continuous casting process.
3 is a schematic view of a rolling material producing apparatus of the continuous casting process of the present invention.
4 is a view showing an example of an end heating apparatus of the present invention.
5A and 5B are views showing an example of the spray cooler of the present invention.
6 is a graph showing the correlation between the residence time and the sectional area reduction ratio (RA) of the rolled material producing apparatus in the continuous casting process of the present invention.
7 is a view showing the internal state of the cast steel with the elapse of the residence time in the horizontal cross-sectional direction of the cast steel specimen.
8 is a view showing the internal state of the cast steel with the elapse of the residence time of the cast steel specimen in the vertical cross-sectional direction.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The shape and size of elements in the drawings may be exaggerated for clarity.

Hereinafter, a rolled material producing apparatus in a continuous casting process according to an embodiment of the present invention will be described in detail with reference to the drawings.

3 to 8, a rolling material producing apparatus of a continuous casting process according to an embodiment of the present invention includes a continuous casting machine 100, a rough rolling mill 200, an end heating apparatus 300, and a controller (not shown) And may additionally include a spray cooler 400.

The continuous rolled material producing apparatus includes a continuous casting machine 100 for producing a cast steel S, a rough rolling mill 200 for intermediate rolling the cast steel S produced in the continuous casting machine 100 to produce a rolled material, An end heating apparatus 300 disposed in the moving path of the slab S passing through the player 100 and moving to the roughing mill 200 to heat an edge of the slab S, (Not shown) for controlling the residence time of the slab S from the exit of the slab 100 to the entrance of the roughing mill 200 to satisfy the following expression (1).

The casting machine 100 supplies molten steel to a casting mold to form a solidified shell, and then, in a segment region in which a plurality of segments composed of a plurality of pairs of guide rolls and drawing rolls are successively arranged, casting is performed using cooling water injected through a spray nozzle S) is directly cooled to cast the cast slab (S). The player 100 is constructed so that solidification can be completed to the inside of the slab S in the segment area.

The rough rolling mill (200) is a facility for intermediate rolling the cast (S) produced in the continuous casting machine (100) to produce a rolled material. The cast steel S produced by the machine tool 100 can be intermediate rolled by the roughing mill 200 and rolled into a rolled material. The rolled material rolled by the roughing mill 200 is also called a rolled bar.

The rough rolling mill (200) has a rolled portion having at least two rotating rolls. Whereby the slab S passes between two rotating rolls. At this time, it is possible to increase or decrease the slab S by applying a continuous force while gradually narrowing the gap between the rolls.

That is, the roughing mill 200 having two rolling sections is shown in FIG. 3, but the present invention is not limited thereto. The roughing mill 200 may have fewer or larger number of rolling sections. The thickness of the slab S is reduced by the above rough rolling mill 200, and a rolling bar having a wider width can be produced.

When the slab S produced in the continuous casting machine 100 is rolled in the rough rolling mill 200, the minimum temperature of the slab S must be maintained at a predetermined temperature or higher. In order to prevent temperature fluctuations in the width direction of the cast steel S produced in the continuous casting machine 100 and to prevent defects such as whales that may occur when rolling the rolled material in the roughing mill 200, Device 300 may be required.

The end heating apparatus 300 is disposed in the moving path of the slab S passing through the platen 100 and moving to the rough rolling mill 200 to heat the edge of the slab S. [

4, the end heating apparatus 300 locally heats the end of the slab S in the process of moving the slab S produced in the performance machine 100 to the roughing mill 200, The temperature of the central portion and the end portion of the slab S can be made constant, thereby eliminating the temperature deviation in the width direction of the slab S.

The reason why the end heating apparatus 300 is installed between the continuous casting machine 100 and the roughing mill 200 is that the end heating apparatus 300 is installed between the continuous casting machine 100 and the roughing mill 200 , And when the temperature of the edge of the slab S is increased, a sufficient value of the sectional area reduction rate can be ensured even within a short residence time.

Sectional area reduction ratio RA is a value indicating the ratio of the cross-sectional area of the slab S reduced by the rolling in the roughing mill 200 in the raw area of the slab S, The possibility of occurrence of a crack or the like on the surface of the rolled material produced in the roughing mill 200 can be remarkably reduced.

The cross sectional area reduction rate can be increased when the FeS of the cast (S) is converted into MnS. However, when the slab S has a residence time equal to or shorter than the residence time according to the above formula (1), the time for converting FeS to MnS is insufficient, and the slab S in the roughing mill 200 is rolled, Quality defects such as cracks may occur on the surface of the substrate.

7 is a photograph showing the internal state of the slab S with the elapse of the residence time in the horizontal cross-sectional direction of the slab S specimen.

As shown in the photograph on the left side of FIG. 7, when the retention time is 0 minute, MnS or S exists in a linear or plate form in a segregation part appearing white, and segregated parts both in the grain and grain boundaries are observed, S is estimated to be large. Therefore, when a large number of linear or plate-like segregates are connected to each other, cracks are likely to occur.

As shown in the photographs at the center and the right of Fig. 7, it is observed that as the residence time becomes longer, the segregation of S, P, MnS gradually changes to a circular shape, Ductility can be improved.

8 is a photograph showing the internal state of the slab S with the elapse of the residence time of the specimen S in the vertical section direction.

As shown in the photograph on the left side of Fig. 8, when the retention time is 0 minutes, the segregation layer is observed prominently on the upper part of the specimen S, and the ductility is poor because the segregation part MnS is linear or plate- Cracks can easily propagate along the segregation zone if cracking begins at the segregation.

8, a linear or plate-shaped segregation part MnS observed at a retention time of 0 minutes is more sporadically observed, so that ductility is improved. As compared with when the retention time is 0 minute, The degree of propagation of the electromagnetic waves can be alleviated.

As shown in the photograph on the right side of Fig. 8, no linear or plate-shaped segregation part MnS observed at the retention time 0 minutes is observed. Therefore, ductility is improved in comparison with the photograph in the center of FIG. 8 because there is no segregation or precipitate in a connected form.

As shown in the photograph of Fig. 8, as the residence time becomes longer, the segregation becomes dispersed, and the ductility at high temperature can be improved due to such a morphological change.

The end heating apparatus 300 may be configured to heat the upper side edges and the lower side edges of the cast steel S, respectively. The end heating apparatus 300 may be configured to heat two edges on the upper side of the cast steel S and two edges on the lower side thereof by a single end heater 300.

As shown in FIG. 4, the end heater 300 may be provided with a plurality of heating devices for heating upper side edges and lower side edges of the cast steel S, respectively.

The end heating apparatus 300 is provided with four heating devices for heating the upper side edges and the lower side edges of the cast steel S and the four heating devices are controlled to be simultaneously heated .

Here, the end heater 300 locally heats the edge portion of the steel strip S which is likely to cause defects. At this time, the edge of the cast steel S having a temperature lower than that of the central portion of the cast steel S produced from the console 100 is locally heated by the end heating apparatus 300 to raise the temperature in the width direction of the steel S By making the distribution uniform, it is possible to reduce the various defects, thereby preventing the productivity from being lowered due to the shutdown of the operation, and reducing the production cost of the rolled material due to the extension of the operating time and the increase of the consumption amount of the material.

Further, if the temperature of the edge of the slab S is sufficiently raised, there is an effect that the blooming region can be avoided when the slab S is rolled by the roughing mill 200.

The control section (not shown) can control the residence time of the slab S from the exit of the performance machine 100 to the entrance of the roughing mill 200 by the following equation (1).

Equation (1)

Where t is the residence time of the slab S from the exit of the continuous casting machine 100 to the entrance of the roughing mill 200 and T is the time at which the slab S on the exit side of the continuous casting machine 100, The lowest temperature of the surface (캜).

The reason why the control section (not shown) controls the residence time of the slab S from the exit of the stationery machine 100 to the entrance of the roughing mill 200 is that the residence time affects the ductility of the slab S (Reduction in Area, RA).

Accordingly, by providing the end heater 300 between the continuous casting machine 100 and the roughing mill 200, the temperature of the edges of the slab S is increased, so that a sufficient value of the sectional area reduction rate can be ensured even within a short residence time have.

The control unit (not shown) can control the residence time of the slab S so that the reduction rate of the cross-sectional area of the slab S approaches 100%.

6, when the minimum temperature of the slab S is 1200 ° C., the residence time of the slab S from the exit of the continuous casting machine 100 to the entrance of the rough rolling mill 200 is 4 minutes And controls the residence time of the slab S from the exit of the continuous casting machine 100 to the entrance of the roughing mill 200 to 6.3 minutes when the minimum temperature of the slab S is 1100 ° C, If the minimum temperature of the slab S is 1000 ° C. and the residence time of the slab S from the exit of the continuous casting machine 100 to the entrance of the roughing mill 200 is controlled to be 20 minutes, The cross sectional area reduction rate is close to almost 100%.

Under such a condition, when the slab S is rolled from the roughing mill 200, quality defects such as cracks hardly occur on the surface of the rolled strip.

The rolled material producing apparatus of the continuous casting process may further include a spray cooler 400 disposed at the rear end of the rough rolling mill 200 to adjust the amount of cooling of the rolled material produced in the rough rolling mill 200 in the width direction have.

The spray cooler 400 is a facility for adjusting the cooling amount in the width direction of the rolled material rolled in the roughing mill 200.

The spray cooler 400 can further prevent local defects during rolling by the finishing mill after the rolling step by the roughing mill 200 by adjusting the temperature fluctuation in the width direction locally raised by the end heating apparatus 300. [

The spray cooler 400 may cool the rolled material by spraying a coolant through an injection port spaced apart at a predetermined interval.

As shown in FIG. 5A, the spray cooler 400 may be provided with a spray cooler 400 continuously installed at the center and the edge of the rolled material. At this time, more coolant is injected through the injection port provided at the edge of the rolled material, so that the amount of cooling at the edge is larger than the amount of cooling at the central portion of the rolled material, and the temperature variation in the width direction of the rolled material can be controlled.

5B, the spray cooler 400 includes an end spray cooler 410 disposed at both sides of the upper and lower sides of the rolled material to spray a coolant to the edge of the rolled material, A central spray cooler 420 disposed at a central portion for spraying a coolant to a central portion of the rolled material and an end portion spray cooler 410 for controlling a cooling amount of the end portion spray cooler 410 and the center portion spray cooler 420, And a cooler control unit (not shown) for controlling the amount of coolant injected through the center spray cooler 420.

The end portion spray cooler 410 and the center portion spray cooler 420 may be controlled so that the injection amount of the coolant is controlled.

A cooler controller for controlling the amount of coolant injected through the end portion spray cooler 410 and the center portion spray cooler 420 so as to adjust the cooling amount of the end portion spray cooler 410 and the center portion spray cooler 420 Not shown). At this time, the cooler control unit (not shown) controls both the end spray cooler 410 and the center spray cooler 420 so that more coolant is sprayed to the edge of the rolled material so that the edge of the rolled material is cooled more Can be controlled.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. And will be apparent to those skilled in the art.

100: Player 200: rough rolling mill
300: end heater 400: spray cooler
410: End Spray Cooler 420: Central Spray Cooler
S: Casting

Claims

Castors producing castings:
A roughing mill for intermediate rolling the cast steel produced in the casting machine to produce a rolled material;
An end heater disposed in a traveling path of the casting which passes through the casting machine and moves to the roughing mill to heat an edge of the casting; And
And a controller for controlling the residence time of the casting from the exit of the casting machine to the entrance of the roughing mill to satisfy the following expression (1).

The apparatus according to claim 1,
And a plurality of heating devices for heating upper side edges and lower side edges of the cast steel, respectively, in a continuous casting step.

The method according to claim 1,
Further comprising a spray cooler disposed at a rear end of the rough rolling mill for adjusting a cooling amount in a width direction of the rolled material produced in the rough rolling mill.

4. The sprayer according to claim 3,
An end spray cooler disposed at both side edges of the upper and lower portions of the rolled material and spraying a coolant to an edge of the rolled material; And
A central spray cooler disposed at a central portion of the rolled material and spraying a coolant to a central portion of the rolled material; And
And a cooler control unit for controlling an amount of coolant injected through the end portion spray cooler and the center portion spray cooler so as to control a cooling amount of the end portion spray cooler and the center portion spray cooler, Serial production equipment.