KR20140085166A - Rolling mill and rolling method - Google Patents

Abstract

Provided are an apparatus and a method for rolling a super thick steel plate capable of rolling a super thick steel plate by applying larger rolling pressure within the limited capacity of a mill, and deforming a super thick steel plate toward the central part in a thickness direction. The apparatus for rolling a super thick steel plate comprises a transferring table transferring a material; and a rolling unit installed on the transferring table to roll the material. The rolling unit includes a different shaped mill having different shaped rolls which have the diameters of the central parts relatively larger than that of the both side parts to pressure the central part of the material in an axial direction.

Description

ROLLING MILL AND ROLLING METHOD BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a rolling mill. More particularly, the present invention relates to an extreme post-rolling mill capable of manufacturing extreme post-rolling, and a rolling method.

Generally, the rolled steel sheet is produced through heating, rolling, cooling, and calibrating processes in the post-rolling process, and it is generally manufactured in accordance with the thickness of the rolled steel sheet, such as a thin steel plate (thickness: Steel plate (thickness: 40mm or more).

In the reverse rolling of the steel sheet, the hot slab is extruded and rolled by a rolling mill. Such a steel sheet rolling method is a method in which rolling reduction and total number of passes for rolling pass are determined from slab dimensions, product dimensions, and facility limit values (equipment load and equipment torque) of the rolling mill before processing the steel strip, And the material is rolled. This process is repeated until the last pass after every pass rolling.

In general, the thickness of the slab used in the steel sheet rolling process is fixed, and the total rolling reduction (= slab thickness-product thickness) to be rolled decreases as the thickness of the product increases. That is, the total rolling reduction is reduced as the post material increases, but the rolling pass always has to be an integer. Therefore, in the case of a thick steel plate, the reduction rate per pass tends to be small. In addition, in the case of a large thickness steel sheet, a greater force (rolling load) and energy (power) are required to impart the same amount of rolling reduction as compared with a steel sheet. In general, the rolling reduction per pass can not be greater than the value determined from the equipment capacity (equipment load, motor power) of the rolling mill. Also, when the thickness is larger than that of the thin steel sheet, the rolling deformation hardly penetrates to the central portion of the thickness, so that the possibility of nonuniformity in the internal quality in the thickness direction is remarkably increased. This deformation characteristic is the reason that the thickness of the steel plate is limited in a rolling mill with limited facility capacity. Generally, as the physical limit of the rolling mill, the pressure ratio (the ratio of the thickness of the slab to the thickness that can be produced by the product using the slab) It is called a pharmaceutical.

Therefore, there is a need for a manufacturing technique capable of infiltrating deformation to the center of thickness by applying a downward pressure per pass of extreme post material using a steel plate mill having a limited facility capability.

Therefore, in order to increase the reduction rate of the rough rolling pass during the production of the extreme steel plate, a technique for setting the reduction amount close to the equipment value of the conventional rolling mill has been developed. However, this technique has limitations in the application of the coercive force lowering rate because the equipment values (equipment load and equipment torque) of the coarse rolling mill are determined at the initial stage of the rolling mill introduction, and thus they are independent of recent extreme steel plate production.

In order to replace the aging mill facilities, steel mills have recently become larger and construction costs and construction costs are also increasing. However, it is very difficult to retrofit or newly build a new steel plate in the world market, which is a surplus supply of demand. In spite of the fact that the equipment limit of the rolling mill is increased, the steel sheet mill is constantly faced with limitations in facility capacity due to the change in required characteristics of the steel plate (high strength, high toughness,

In addition, as a manufacturing technique capable of penetrating deformation to the center of the thickness, it is possible to manufacture a steel sheet having a good porosity by using a method of forging a thickness and a width of a slab before rolling in the production of extreme- A method of alternately performing the thickness terminal and the widthwise forging, and then performing the rolling. However, in the case of thickness reduction and extreme pressure using a forging machine, a separate device other than the rolling mill (single stage, roller table, large tongs for rotating the slab for width forging, single stage cooling device, etc.) is required. Further, in order to impart a high reduction load per pass under a limited short-term equipment load condition, it is inevitable to reduce the die length and forging speed of the short- Therefore, the process of rolling down the entire length of the slab using a forging machine requires a great deal of continuous forging and causes an excessive temperature deviation in the longitudinal direction of the slab. Further, the thickness of the material after forging has a deviation in the longitudinal direction of the slab according to the wear of the forging die, and if it is severe, lapping of the material may occur.

As described above, the work rolls of the post-roll rolling system used in the technique of applying the secondary deformation by using the conventional rolling system after giving the initial deformation by using a rolling machine having a large facility capability or by using a forging machine, And a barrel end having a rectangular cross section having the same diameter. At this time, the contact width of the material and the roll is almost the same as the width of the material entering the rolling mill. In addition, the reduction amount per pass determined from the equipment load of the rolling mill is inversely proportional to the contact width of the material and the roll. Therefore, the rolling reduction rate in the conventional steel sheet rolling mill using the flat roll is limited by the size and material width of the rolling mill facility. More specifically, when the slab thickness and the product thickness are determined, the total number of passes to be rolled and the average rolling reduction are determined. However, in the conventional case, there was no method other than to raise the capacity of the rolling mill when the average rolling reduction rate is smaller than the material required limit rolling reduction rate.

Therefore, it is required to develop a steel sheet rolling technology capable of overcoming the manufacturing limit of the extreme steel sheet determined from the compressive strength (ratio of slab thickness to product thickness), which is the physical limit of the rolling mill.

Accordingly, it is possible to provide a steel plate rolling mill and a rolling method capable of rolling a steel plate at a large amount under a limited facility capacity of the rolling mill.

The present invention also provides an extreme post-rolling system and rolling method capable of penetrating deformation to the center portion of the extreme post material.

The rolling facility includes a transfer table for transferring a material and a rolling section provided on the transfer table for rolling the material,

The rolled portion may include a mold release mill having a mold release work roll for pressing the center of the material relatively larger in diameter at the central portion along the axial direction than the diameter of the both side portions.

Wherein the rolling section includes a mold release mill having a mold release work roll for pressing a center portion of the material so that the diameter of the center portion is relatively larger than the diameter of both side portions along the axial direction, And a balancing mill with the same balancing work roll.

The rolling section may be disposed at the front side of the balance mill along the outward direction from the entrance side of the conveyance table.

The rolled portion may be disposed behind the balance mill along the outward direction from the entrance side of the conveyance table.

The rolling facility may further include a finishing mill installed on the conveying table for finishing rolling the material passed through the rolling mill.

The rolling facility may further include a vertical mill installed on the transfer table to control the spreading of the material passing through the rolling section in the width direction.

The vertical mill can be disposed on the exit side of the profile mill along the moving direction of the work.

The material may be a steel plate having a thickness of 40 mm or more or a steel plate having a thickness of 100 mm or more.

The present rolling method includes a rolling step of passing a material through a rolling machine at least once to deform the material in the thickness direction,

The rolling step may include a central depressurizing step of depressing the center portion along the material width direction at the time of one pass of the material and deforming the depressed material by depressing both sides of the depressed material.

The rolling step may further include a normal pressing down step of pressing down the front face in the width direction of the workpiece when the work is passed.

The rolling step may further include a vertical rolling step of controlling lateral spreading of the material through the side lowering step.

The method may further include a step of press-rolling the material subjected to the rolling step.

According to the present embodiment as described above, even if the reduction rate per pass is the same under a limited facility capacity, the penetration of deformation into the center portion of the thickness can be made larger.

Thus, it is possible to manufacture a steel sheet having a high quality (high strength, high toughness, weldability) uniform in the thickness direction with respect to the steel sheet having a large thickness during the steel sheet rolling.

In addition, it will be possible to overcome the pressure constraint in the production of extreme post-processing materials for existing performance facilities and rolling facilities.

In addition, even if the strength of the extreme steel sheet continuously increases, the capability of the rolling equipment can be enhanced through the replacement of the work roll, and the competitiveness of the continuous rolling equipment can be maintained without installing new rolling facilities or increasing facilities.

1 is a schematic view showing a steel plate rolling mill according to the present embodiment.
FIG. 2 is a perspective view showing a mold-rolling machine provided in a steel plate rolling mill according to the present embodiment.
Figs. 3 to 6 are schematic views showing a steel plate rolling mill in another embodiment. Fig.
FIGS. 7 to 9 are views for explaining the rolling process of the steel sheet according to the present embodiment.
10 is a view showing the shape of the rolled material according to the present embodiment in comparison with the conventional one.
Fig. 11 is a diagram showing the deformation rate of the rolled material according to the present embodiment in comparison with the conventional one.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Wherever possible, the same or similar parts are denoted using the same reference numerals in the drawings.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

All terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Hereinafter, the steel plate rolling equipment of this embodiment will be described by taking as an example a steel plate rolling apparatus having a thickness of 100 mm or more as an example. However, the present invention is not limited to this and is also applicable to a steel sheet having a thickness of 40 mm or less.

FIG. 1 is a schematic view showing a steel plate rolling mill according to the present embodiment, and FIG. 2 shows a mold-turning mill provided in a rolling mill according to the present embodiment.

1, the rolling facility 100 of the present embodiment includes a transfer table 10 for transferring a work P and a rolling section 20 provided on the transfer table 10 for rolling a workpiece . The rolled portion 20 continuously rough-rolls the material such as the extreme-side steel sheet.

In the present embodiment, the rolled portion 20 includes a release work roll 23 having a diameter at the center along the axial direction that is relatively larger than the diameter of both side portions and pressing the center of the material, And a backup roll 24 which is continuously disposed with the above-described shaping mill 21 and which supports a balance working roll 24 and a balancing working roll 24 having the same diameter along the axial direction, And a balance mill 26 provided with a flat bed. Thus, the center of the work is pressed down in the width direction through the shaping mill 21, and the width side portion is pressed down while continuously passing through the balance mill 22.

The rolling section 20 has a structure in which a shaping mill 21 is disposed in front of the balancing mill 22 along the outward direction from the entrance side of the conveying table 10.

As shown in Fig. 2, the mold releasing work roll 23 provided in the shaping mill 21 has a structure in which the diameter of the center portion along the axial direction is relatively larger than the diameter of both side portions.

As the diameter of the central portion of the release work roll 23 is relatively large, the release work roll 23 has a deformed cross-sectional structure, so that the widthwise deformation of the material can be restrained during rolling of the material such as the extreme- .

The release work roll 23 is rolled by applying a press load to only the center portion of the work by the protruding central portion, and the both side portions are not rolled due to the pressure being not applied to the work. Thus, the mold-rolling mill 21 is rolled only in the central portion of the material, and the material is rolled into a cross-sectional shape having a concave central portion.

The degree of protrusion of the central portion of the releasing work roll 23 and the length of the releasing work roll 23 may vary depending on the thickness and strength of the material, and are not particularly limited.

The back-up roll 25 for supporting the release work roll 23 is applicable to both a release structure in which the center portion is recessed so as to correspond to the release work roll 23 or a flat structure having the same diameter along the axial direction.

The balancing mill (22) is a mill equipped with a general balancing work roll (24) having the same diameter along the axial direction. The balancing work roll 24 is pressed against the workpiece in the form of a flat rectangular cross section along the axial direction.

The material P to be moved along the conveying table 10 is rolled while passing through the rolling section 20 composed of the shaping rolling mill 21 and the equilateral rolling mill 22 one or more times.

The rolled portion 20 of the present embodiment is formed by a pair of a forming die 21 and a balancing mill 22 so that the reduction rate per pass is the same as the conventional one, The penetration of the deformation is further increased, and it is possible to manufacture the extreme steel sheet having uniform quality in the thickness direction. Here, the pass means that the work has passed the rolled portion 20, and the pass when the work P passes the rolled portion 20 once is referred to as one pass.

That is, in the rolling section 20 of this embodiment, the amount of reduction to be applied to the workpiece in one pass is divided by two successive mold release mills 21 and a balance mill 22, The rolling machine 22 can increase the reduction rate by making the contact width between the work and the work roll smaller than the inlet width of the work. In addition, since only the center portion of the material is pressed while passing through the profile mill 21, and only the opposite side portions of the unstretched material are rolled after passing through the balancing mill 22, the unstretched portion of each rolling mill works as a support, The penetration of deformation to the center portion can be made larger.

Here, the rolling facility may further include a finishing mill 40 installed on the transfer table 10 for finishing and rolling the material passed through the rolling section 20. The finishing mill 40 passes the rolling section 20 at least once to finish-roll the material rolled to a predetermined thickness. The material passes the finishing mill 40 at least once.

The rolling mill further includes a vertical mill 30 installed on the transfer table 10 for controlling the spreading of the material through the rolling mill 20 in the width direction.

In the present embodiment, the vertical mill 30 is disposed on the exit side of the profile mill 21 along the direction of movement of the work. As shown in FIG. 1, the vertical mill 30 is disposed at the rear end of the balance mill 22 from the entrance side to the exit side of the conveyance table 10. The vertical mill 30 controls the excessive width spreading of the workpiece when the workpiece is rolled through the die-cut mill 21 and the balance mill 22.

A side guide 50 for securing the centering of the rolling mill and the material before rolling is disposed at the entrance side of the rolling section 20 and the finish rolling mill 40.

Fig. 3 shows a rolling facility of another embodiment.

As shown in Fig. 3, the rolling facility of this embodiment is such that the rolling section 20 is disposed behind the flat-bed mill 22 in the direction of the exit from the inlet side of the conveying table 10 have.

Since the rolling facility of this embodiment is the same as the embodiment of Fig. 1 except for the arrangement structure of the mold-rolling mill 21 and the balance mill 22, the same reference numerals are used for the same constituents, do.

3, the vertical mill 30 is disposed in front of the balance mill 22 as the shaping mill 21 is disposed behind the balance mill 22. In FIG. The vertical mill 30 controls the excessive width spreading of the material when the side of the material is rolled by passing the material P through the forming mill 21 and the baling mill 22.

Fig. 4 shows a rolling facility for use in, for example, a heavy plate mill, with a structure having one rolling section 20 to complete the rough rolling process and the finish rolling process.

The rolling facility shown in the embodiment of Fig. 4 includes a conveying table 10 for conveying the material P and a rolling section 20 provided on the conveying table 10 for rolling the material. The rolled portion 20 is subjected to continuous rough rolling of the material such as the extreme-side steel sheet and then to finish rolling.

The rolling unit 20 includes a release roll 23 and a back-up roll 25 for supporting the release work roll 23, the diameter of which is relatively larger at the center along the axial direction than the diameter of both sides, And a backup roll 26 which is disposed continuously with the above-described shaping mill 21 and supports the equalizing work roll 24 and the equalizing work roll 24 having the same diameter along the axial direction, And a balancing mill (22) equipped with the same. Thus, the center of the work is pressed down in the width direction through the shaping mill 21, and the width side portion is pressed down while continuously passing through the balance mill 22.

The rolling section 20 has a structure in which a shaping mill 21 is disposed in front of the balancing mill 22 along the outward direction from the entrance side of the conveying table 10.

The rolling mill further comprises a vertical mill (30) installed on the transfer table (10) and controlling the spreading of the material through the rolling mill (20) in the width direction.

In the present embodiment, the vertical mill 30 is disposed on the exit side of the profile mill 21 along the direction of movement of the work. As shown in FIG. 4, the vertical mill 30 is disposed at the rear end of the balance mill 22 from the entrance side to the exit side of the conveyance table 10. The vertical mill 30 controls the excessive width spreading of the workpiece when the workpiece is rolled through the die-cut mill 21 and the balance mill 22.

A side guide 50 for securing the centering of the rolling mill and the material before rolling is disposed at the entrance side of the rolling section 20 and the finish rolling mill 40.

Fig. 5 shows another embodiment of the rolling facility shown in Fig.

5, the rolling facility of this embodiment has a structure in which the rolling section 20 is disposed behind the flat-bed mill 22 in the outward direction from the entrance side of the conveying table 10 have.

Since the rolling facility of this embodiment is the same as the embodiment of Fig. 4 except for the arrangement structure of the mold-rolling mill 21 and the balance mill 22 as described above, the same reference numerals are used for the same constituents, do.

5, the vertical mill 30 is arranged in front of the balance mill 22 as the shaping mill 21 is disposed behind the balance mill 22. In FIG. Accordingly, the vertical mill 30 is controlled to have an excessive spread of the material when the side of the material is rolled while passing through the die-rolling mill 21 and the flat mill 22.

Thus, in this embodiment, the material is rough-rolled while passing through the shaping rolling mill 21 of the rolling section 20 and the equilibrating rolling mill 22 a plurality of times, and in the final rolling step, the shaping rolling mill 21 opens the roll gap And the finish rolling is performed only by the equilibrium rolling mill 22.

Fig. 6 shows a rolling facility of another embodiment.

6, the rolling facility of this embodiment includes a conveying table 10 for conveying a material P, a rolling section 20 provided on the conveying table 10 for rolling the material, a rolling section And a finishing mill 40 for finishing and rolling the workpieces.

The rolling section 20 is composed of a single die-cut mill 21 without using a plurality of mills. The die-rolling mill 21 has a central portion having a diameter larger than a diameter of both side portions along the axial direction, And a back-up roll (25) for supporting the release work roll (23) and the release work roll (23).

In the present embodiment, a work roll of a rough rolling mill is replaced with a release work roll 23 without a separate type mill in a conventional roughing mill having one rough rolling mill and one finished steel mill, It is a structure to use.

The rolling mill is provided with a vertical mill 30 for controlling the spreading of the work in the width direction in front of the forming mill 21 and the finishing mill 40 along the conveying table 10.

In Fig. 6, the work is roughly rolled through a shaping mill 21 and deformed into a concave cross-sectional shape. In this state, the work is transferred to a finishing mill 40 and rolled into a flat rectangular cross-sectional shape through a finishing mill 40.

Hereinafter, the rolling process of the present embodiment will be described with reference to FIGS.

First, in order to facilitate understanding of the rolling method of the present embodiment, a roughness rolling of five passes in total in the conventional rough rolling process will be described as an example. Conventional rough roll mills are made through a single rolling mill with a flat roll having the same diameter along the axial direction. Thus, the entire front side in the width direction is rolled (hereinafter, referred to as normal rolling) by the flat roll. Prior to rolling, the material is vertically rolled through a vertical rolling mill located at the front of the rolling mill, and then subjected to one-pass horizontal rolling through the rolling mill. The rolled material after one pass has a rectangular cross-section.

After one pass, the material is moved in the opposite direction and subjected to 2-pass horizontal rolling through the rolling mill. This rolling sequence is carried out until a total of five passes are made, and the outgoing cross section of the rolling mill is square for each rolling pass. In order to prevent slip defects on the material surface due to the difference in rolling speed between the vertical mill and the rolling mill, the rotation speed of the vertical mill synchronizes with the speed of the mill or is smaller than that of the mill I have.

In addition, when a slab having a short length is strongly pressed by using a conventional rolling mill, two contact between the material and the work roll occurs during rolling, resulting in a misrolling phenomenon between the rolling mills and excessive plate lifting or plate deflection A defect having a bulge shape in the longitudinal direction is generated. In order to prevent this, in the conventional rolling mill, the reduction amount of one pass is set to be weak. Further, in the conventional case, the energy transferred to the material according to the rolling deformation during the time during which the material is fed for the next pass rolling after the current pass rolling makes the grain refinement to reduce the grain size inside the material by the static recrystallization phenomenon . However, in the case of a conventional steel sheet rolling mill, there is a disadvantage that the energy transmitted to the material is limited to the vicinity of the surface of the steel sheet, and therefore there is a possibility that the crystal grain in the steel sheet thickness direction becomes uneven.

In contrast to the conventional rolling method, the rolling method of the present embodiment includes a step of rolling a material, and the rolling step includes a central lowering step in which the central part is deformed by being rolled along the material width direction during one pass of the material, And a side lowering process in which both sides of the workpiece are pressed down and deformed.

In addition, the main rolling process may further include a normal rolling process in which the entire surface in the width direction of the workpiece is deformed by being deformed.

As shown in FIG. 7, the main rolling process is a primary down-rolling through a mold-lowering process 21, a center-down direction in the material width direction, and a continuous down- The steel sheet is passed through the rolling section 20 while being subjected to a secondary downwardly pressing process and both sides of the material in the widthwise direction of the unmachined part are subjected to secondary pressure rolling.

The material having passed through the balance mill 22 passes through a non-driving vertical mill 30 located at the rear end of the steel mill, and undergoes a vertical rolling step in which the width thereof is controlled.

Unlike the conventional rolling mill, the first intermediate rolled intermediate material has a concave symmetrical cross-sectional shape in the first pass, and the first rolled material has a square cross-sectional shape.

In this embodiment, the contact width of the material which is in contact with the release work roll 23 and the balancing work roll 24 while passing through the shaping mill 21 and the balance mill 22 is smaller than the pre-rolling width. Therefore, it is possible to give a greater reduction in the amount of rolling reduction in the conventional rolling mill in which the facility capacity is limited in each of the forming mill 21 and the balancing mill 22. In the present embodiment, one pass of the continuous roughing rolling is a process in which a portion and a portion of the material other than the entire material are rolled (hereinafter referred to as a pressure-weakening) more strongly than conventional normal rolling, . After the lowering by the shaping mill 21, the lowering of the secondary side by the balancing mill 22 is continuously performed. Here, dynamic recrystallization occurring during secondary rolling and static recrystallization after 1-pass rolling may occur. This recrystallization phenomenon is well known in hot-rolled strip rolling machines for continuous rolling. Therefore, the grain size of the material can be made even more uniform in the thickness direction than in the rolling method using the conventional rolling mill.

Further, unlike a case where a slab having a short length is pressed down by using a conventional rear steel plate rolling machine, in the present embodiment, both side portions in the width direction of the material are not rolled during rolling under the central down- In the lower process, the center portion in the width direction of the material is not rolled. These characteristics can solve the problems of the conventional post-rolling mill by restraining the longitudinal deformation of the material in the lower part of the low pressure in each rolling mill.

The 1-pass rolled material is moved in the reverse direction and passed through the rolling section 20 to be rolled in two passes.

In the 2-pass rolling, the material is subjected to the primary rolling through the balancing mill 22 and the primary rolling, and the secondary rolling is performed by the secondary rolling mill 21 to carry out the forced rolling. In other words, the two passes are subjected to the pressure rolling process by the central down-pressure process after the normal rolling by the normal down-pressure process. Further, unlike the one-pass type, the intermediate material which is primarily rolled in the two passes has a rectangular cross-sectional shape, and the material that has been rolled after two passes has a concave symmetrical cross-sectional shape.

The 2-pass rolled material is again moved forward and passes through the rolling section 20 to be rolled three passes.

In the 3-pass rolling, the material is first rolled through the mold release mill 21 and then continuously rolled through the equilateral-scale rolling mill 22. The shaping and rolling machine 21 primarily rolls the material having a concave cross-sectional shape over the entire widthwise direction including both the center in the width direction and the both side portions unlike the one-pass method. That is, the rolling by the die-casting mill 21 is a normal rolling-down process in which the entire widthwise surface of the workpiece is pressed down and deformed. The sides of the flat steel mill 22 are subjected to the second pressing process only in the width direction sides of the material having the concave symmetrical cross-sectional shape through the rolling process.

As shown in FIG. 7, the material having passed through the continuous roughness rolling system finally has a rectangular cross-sectional shape. In this embodiment, the material can be rolled sufficiently with a smaller number of passes than in the prior art. After 3 passes, the material finishes the rolling process and finally completes the rolling process.

FIG. 8 shows a process for rolling a slab when the surface quality of the slab produced in the continuous casting process is poor.

As shown in Fig. 8, in the rolling step of this embodiment, the roll gap of the shaping and rolling mill 21 is opened in one pass and two passes of roughing rolling, and ordinary rolling is performed through a normal rolling process only with the ball rolling mill 22, Rolling is continuously performed from the path by the shaping mill 21 and the equilibrating mill 22. The continuous rolling process by the shaping mill 21 and the equilibration mill 22 is as described above. In other words, the material is rolled through a central depressurization process in which the center portion is deformed by pressing down the central portion along the material width direction, and a side depressurization process in which both sides of the depressed material are deformed by deformation.

Fig. 9 shows a rolling process in a steel plate rolling mill equipped with a single die-rolling mill 21 and a finishing mill 40. Fig.

As shown in Fig. 9, the central portion of the material in the width direction is rolled down by one pass to pass through the process of undergoing the central depressurization through the mold-type rolling mill 21, and after two passes and three passes, The material having a cross-sectional shape is usually rolled over the entire widthwise direction including both the widthwise center portion and both side portions. The rolling by the shaping and rolling machine 21 is a normal descending process in which the entire widthwise surface of the workpiece is pressed down and deformed. After three passes, the material having a concave symmetrical cross-sectional shape is conveyed to the finishing mill 40 and subjected to a finish rolling process. In the finishing rolling process, one pass is subjected to a side down pressure process. Through the process of side depressurization, the material is rolled in the form of flat anti-rectangular cross-section only by the side of the width direction. Thereafter, the finishing mill 40 is finely rolled to a predetermined thickness by passing a plurality of times.

Figs. 10 to 13 show the shape and strain rate of the rolled material according to the present embodiment in comparison with the prior art.

The material used for rolling is a temperature of 1150 ° C, a thickness of 300 mm, and a width of 2000 mm. The working roll diameter of the rolling mill is 1060 mm and the rolling speed of the rolling mill is 2.1 m / sec.

In the comparative example, single pass rolling was performed using a single rolling mill to apply a 20% reduction rate to the entire width of the material.

In the embodiment, the 20% reduction rate is the same as that of the comparative example, and the continuous secondary rolling in which the both sides of the workpiece in the width direction of the workpiece are rolled by using the balance mill 22 after rolling the central portion in the widthwise direction of the workpiece using the above- .

As shown in FIG. 10, it can be seen that the size of the deformation of the cross section of the workpiece greatly increased after the continuous pass rolling of the embodiment as compared with the comparative example.

Also, as shown in FIG. 11, it can be seen that the rolled load is smaller in the case of the continuous rolling of the center portion of the material and the rolling of both sides in the continuous rolling.

As shown in FIG. 12, in the case of rolling at the central portion in the material width direction, the strain penetration of 1.4 times or more as compared with the strain of the comparative example was increased, and when rolling the both sides in the material width direction, Which is 1.6 times higher than that of the previous example. As a result, it can be confirmed that the present embodiment increases the size of deformation to be infiltrated into the inside of the material under the same pressing force.

Fig. 13 shows the magnitude of the deformation as it goes from the center of the material to both sides at the center in the thickness direction of the material. As shown in FIG. 13, this distribution is also improved in comparison with the comparative example in the case of the embodiment.

Thus, in this embodiment, in order to overcome the thickness production limit of the extreme cold-rolled steel sheet, a plurality of rolling mills are not simply arranged continuously but the rolling reduction to be pressed in one pass is divided into two consecutive times, It is possible to make the infiltration of the deformation into the central portion of the thickness larger.

Thus, it is possible to overcome the mechanical limit of the rolling mill (ratio of slab thickness to product thickness), and even if the strength of the extreme rear steel plate is continuously increased, the rolling system can be continuously improved It is possible to maintain the competitiveness of the continuous rolling system.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

10: transfer table 20: rolling section
21: profile rolling mill 22: balancing mill
23: Release roll 24: Balancing roll
25, 26: backup roll 30: vertical mill
40: Finishing mill

Claims (11)

1. A rolling facility for producing extreme steel plates, comprising a transfer table for transferring a workpiece and a rolling section provided on the transfer table for rolling a workpiece,
Wherein the rolling section includes a mold release mill having a mold releasing roll for pressing down the center of the material so that the diameter of the center portion is larger than the diameter of both side portions along the axial direction. The method according to claim 1,
Wherein the rolling facility further comprises a finishing mill installed on the transfer table for finishing rolling the material passed through the rolling section. The method according to claim 1,
Wherein the rolling facility further comprises a vertical mill installed on the transfer table to control the spreading of the material through the rolling section in the width direction. The method of claim 3,
Wherein the vertical mill is disposed on the exit side of the shaping rolling machine along a moving direction of the work. 5. The method according to any one of claims 1 to 4,
Wherein the rolling section comprises the shaping mill and a balancing mill disposed continuously with the shaping mill and having a balancing work roll having the same diameter along the axial direction. 6. The method of claim 5,
Wherein the rolling section is disposed at the front side of the balance mill along the outward direction from the entrance side of the conveyance table. 6. The method of claim 5,
Wherein the rolling section is disposed behind the balance mill along the outward direction from the entrance side of the conveyance table. And a rolling step of passing the material through the rolling machine at least once more to deform the material in the thickness direction, the rolling method comprising the steps of:
Wherein the rolling step comprises a central depressurizing step of depressing the central portion along the material width direction when the material passes through the depressing step, and a side depressurizing step of depressurizing both sides of the depressed material to deform. 9. The method of claim 8,
Wherein the rolling step further comprises a normal pressing step of deforming by pressing the material widthwise entire surface. 10. The method according to claim 8 or 9,
Wherein the rolling step further comprises a vertical rolling step of controlling the lateral spreading of the material through the side lowering step. 11. The method of claim 10,
Further comprising the step of finishing rolling the material subjected to the rolling step.

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