JP2018061999A - Pre-rolling pinch roll device and pre-rolling pinch roll method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pre-rolling pinch roll device and a pre-rolling pinch roll method whereby meandering in in-line mill can be hindered when a thin cast piece casted by a twin-drum type continuously casting device for a thin cast piece is fed to the in-line mill and pre-rolled.SOLUTION: A pre-rolling pinch roll device that feeds a thin cast piece to an in-line mill comprises: a first pinch roll R411 in which a first profile PR411 is formed including a first projecting curved shape D111 and a first recessed curved shape D112 that are reduced in diameter from one side L to the other side R of an axis O41; and a second pinch roll R412 in which a second profile PR412 is formed including a second recessed curved shape D121 and a second projecting curved shape D122 increased in diameter from one side L to the other side R of an axis O42. The first pitch roll R411 and the second pinch roll R412 move relative to each other along the axes O41, O42.SELECTED DRAWING: Figure 4A

Description

  The present invention relates to a pre-rolling pinch roll device and a pre-rolling pinch roll method used for feeding a thin cast piece cast by a twin drum type thin cast piece continuous casting apparatus to an in-line mill.

  As is well known, a pair of continuous casting cooling drums (hereinafter referred to as cooling drums) are arranged in parallel, the opposing peripheral surfaces are rotated downward from above, and hot water formed by the peripheral surfaces of these cooling drums. A twin-drum type casting strip continuous casting device is used, which injects molten metal into the reservoir, cools and solidifies the molten metal on the peripheral surface of the cooling drum, and continuously casts thin cast pieces (hereinafter referred to as cast strips). (For example, refer to Patent Document 1).

  As described in Patent Document 1, the twin-drum type casting strip continuous casting equipment solidifies and grows the molten metal poured into the hot water pool on the peripheral surface of the cooling drum while rotating the cooling drum, and forms a casting strip. Send down. The cast strip fed from the cooling drum is fed horizontally by a pinch roll and adjusted to a desired plate thickness by a downstream in-line mill. The cast strip adjusted to a desired plate thickness by the in-line mill is wound in a coil shape by a winding device installed downstream of the in-line mill.

  The in-line mill described in Patent Literature 1 includes, for example, a work roll that is a rolling roll provided so as to face each other with a cast strip interposed therebetween, and a backup roll installed behind the work roll. Moreover, in the example described in Patent Document 1, a hydraulic pressure reduction cylinder is installed in a housing positioned above the backup roll chock above the casting strip.

The hydraulic pressure reduction cylinder has a position detection function for detecting the positions of the work roll and the backup roll, and also has a reaction force meter (load cell). The reaction force from the casting strip 2 makes contact between the work roll and the casting strip. It comes to detect. In addition, a mill hydraulic pressure reduction device is connected to the hydraulic pressure reduction cylinder, and the mill hydraulic pressure reduction device is connected to the overall control device.
The mill hydraulic pressure reduction device can change the roll gap by controlling the hydraulic pressure reduction cylinder based on a command (mill pressure reduction REF signal) from the overall control device.

  The in-line mill starts rolling by tightening the roll gap while rotating the roll of the in-line mill after the tip of the casting strip cast during the steady casting passes through the in-line mill. The rolling method is called flying touch.

Moreover, as shown in Patent Document 1 (FIG. 7), the twin-drum type thin cast strip continuous casting equipment starts a casting by connecting a dummy sheet to the tip of the casting strip and pulling out the casting strip.
In addition, the dummy bar that leads the dummy sheet is formed to be considerably thicker than the strip-shaped slab, and a protrusion that is thicker than the thickness of the cast strip is formed at the connection between the tip of the cast strip and the dummy sheet. ing.
And rolling (flying touch) in an in-line mill is started after the above-mentioned projection part passes an in-line mill.

In the twin-drum type thin cast strip continuous casting equipment, the cooling drum is generally at a low temperature before the start of casting, and when the casting is started, the temperature of the cooling drum is increased by contact with the molten metal.
The cooling drum is cooled from the inner surface by a cooling medium (for example, cooling water) so that the temperature does not exceed a certain temperature, and the period after the temperature of the cooling drum reaches a certain temperature is called steady casting. The temperature of the cooling drum at the time of casting is called a steady temperature, and such a state is called a steady state.

  The profile of the cooling drum changes with the elapsed time from the start of casting to the time of steady casting. Therefore, the profile of the cooling drum is set so that the plate profile (plate crown) of the cast strip at the time of steady casting becomes a desired plate profile.

  FIG. 9 is a conceptual diagram showing a change with the elapsed time after the casting of the cooling drum profile and the casting strip plate profile when the casting strip is manufactured by the conventional twin-drum type casting strip continuous casting equipment. Note that the plate profile of the cast strip shows a form before casting without shifting the cooling drum and performing the reduction in the in-line mill.

  As shown in FIG. 9A, the cooling drum R101 at the start of casting is set to a concave profile in which the central side in the width direction is recessed. As a result, between the cooling drums R101, a casting strip S101 having a plate profile having a convex center in the width direction as shown by hatching is cast.

  Next, after a while has elapsed from the start of casting, as shown in FIG. 9B, the cooling drum R101 expands (expands in diameter) in the center in the width direction due to heat input from the molten metal, and starts casting. Changes to R102, which is a smaller concave profile. Therefore, the plate profile of the cast strip S102 changes to a convex shape having a smaller crown amount than the cast strip S101 at the start of casting.

  Next, after a further time has elapsed from the start of casting and reached a steady state, the cooling drum R102 is further expanded (expanded) by heat input from the molten metal, as shown in FIG. It changes to R103 which is a slightly concave profile. Therefore, the plate profile of the cast strip S103 is changed to a cast strip S103 having a convex shape with a smaller crown amount than the cast strip S102.

  The time from reaching FIG. 9 (A) to FIG. 9 (C) differs depending on the steel type (melting temperature) of the molten metal, the thickness of the casting strip, the rotational speed of the cooling drum and the cooling efficiency. It is about 30 seconds.

  On the other hand, the change in the plate profile of the cast strip includes a change in growth of the solidified shell due to non-uniform cooling of the cooling drum from the start of casting until the steady temperature is reached, in addition to the change due to the thermal expansion of the cooling drum.

  In general, if the cooling on the cooling drum is strong, the thickness of the solidified shell increases and the thickness of the cast strip increases. In the width direction of the cooling drum, the cooling efficiency is higher at the end portion in the width direction of the cooling drum than in the center side in the plate direction of the cooling drum.

  Therefore, the thickness of the solidified shell is greater at the plate end than at the plate center. As a result, in the cast strip after the start of casting, the plate thickness at the plate end is thicker than the plate thickness at the center of the plate, and the portion where the plate thickness at the plate end is thick is called edge-up. This amount of edge-up is greatest at the start of casting, decreases with the elapsed time after the start of casting, and is almost eliminated during steady casting.

  FIG. 10 is a conceptual diagram showing a change in the plate profile of the cast strip due to a change in the growth of the solidified shell until the cooling drum reaches a steady temperature when the cast strip is manufactured by the twin drum type cast strip continuous casting apparatus. is there. In FIG. 10, the change of the cooling drum profile is omitted.

Immediately after the start of casting, the heat at the end in the width direction of the cooling drum is easier to escape than at the center side of the cooling drum, so that the molten metal is greatly cooled at the end in the width direction of the casting strip, and the solidified shell is The end in the width direction is formed thicker than the center in the width direction.
As a result, as shown in FIG. 10A, the plate profile of the casting strip S201 immediately after the start of casting has a large edge-up at the end in the width direction.

After a while after the start of casting, the temperature difference between the center side of the cooling drum and the end in the width direction of the cooling drum becomes smaller than at the start of casting, and the molten metal is cooled at the end in the width direction of the casting strip less than at the start of casting. Thus, the difference in thickness between the center portion and the end portion in the width direction of the solidified shell is smaller than that at the start of casting.
As a result, as shown in FIG. 10B, the plate profile of the casting strip S202 at the time when a certain period of time has elapsed from the beginning of casting forms an edge-up smaller than the casting strip S201 immediately after the start of casting, as shown in FIG.

After a further time has elapsed from the start of casting and the steady state has been reached, the temperature difference between the cooling drum center side and the cooling drum width direction end portion is further reduced, and the thickness of the solidified shell in the width direction center portion and end portion is reduced. The difference is almost gone.
As a result, the plate profile of the cast strip S203 after reaching a steady state after a lapse of time from the start of casting almost eliminates the edge-up as shown in FIG.

  The time required to reach FIG. 10C from FIG. 10A differs depending on the steel type (melting temperature) of the molten metal, the thickness of the cast strip, the rotational speed of the cooling drum, and the cooling efficiency. ) To FIG. 9C, which is about 30 seconds from the start of casting.

  From the above, the plate profile of the cast strip from the start of casting to the time of steady casting is a combination of the crown change due to the thermal expansion of the cooling drum and the edge-up change due to non-uniform cooling of the cooling drum.

  As shown in S301 of FIG. 11 (A), the plate profile of the casting strip is thick at the center in the width direction and at both ends as shown in S301 in FIG. 11 (A), and after a while after the start of casting, S302 in FIG. 11 (B). As shown in FIG. 11, the deviation of the plate thickness decreases, and in a steady state, the plate thickness becomes substantially uniform as shown in S303 of FIG.

  When a cast strip cast in a twin drum thin cast strip continuous casting facility is rolled in an in-line mill, the temperature of the cast strip is about 1000 ° C on the inlet side of the in-line mill. However, the in-line mill does not have a crown control capability enough to accommodate a cast strip of a plate profile as shown in FIG. 11 (A).

  Moreover, in an in-line mill, when a plate profile cast strip as shown in FIG. 11 (A) is rolled with such a large force that the crown amount is adjusted, the plate width center portion and the plate width end portion are thick. Therefore, a large elongation occurs in the longitudinal direction, and the middle elongation at the central portion of the plate width and the end elongation at the end portion of the plate width become extremely large, and as a result, a phenomenon that the cast strip easily breaks occurs.

  Increasing the tension of the in-line mill is effective for plate breakage due to drawing due to the middle elongation of the plate shape in the in-line mill. However, in order to increase the tension of the in-line mill, it is necessary to increase the pressing force of the pinch roll. When the pressing force of the pinch roll is increased, as shown in FIGS. 11 (A) and 11 (B). In some cases, the thick plate portion is rolled.

  If the thick plate portion is rolled, the plate breaks due to meandering with a pinch roll and the plate shape breaks due to drawing with an in-line mill due to severe shape defects. When the plate breaks, the remaining molten metal is immediately discarded, resulting in a great yield reduction.

On the other hand, the casting strip is started in the in-line mill, the casting strip is rolled, and until the desired thickness is reached in the in-line mill, the cast strip is cut off as an off-gauge (out of the plate thickness) in the subsequent process as scrap. It is common to be processed.
As a result, the off-gauge of the cast strip is a major cause of an increase in manufacturing cost due to a decrease in the yield of the cast strip.

  As described above, in order to start the flying touch in the in-line mill earlier and roll the cast strip to the desired thickness stably and efficiently, tension is applied to the cast strip on the entry side and the exit side of the in-line mill. It is effective to apply a load, and the higher the tension, the more effective for preventing meandering and shape defects. To that end, the pinch roll pressing force is increased and the pinch roll pressing force is increased even if the pinch roll pressing force is increased. It is effective not to cause a shape defect.

  As described above, if the pressing force of the pinch roll is increased to lightly reduce the cast strip, the cast strip is stretched asymmetrically in the width direction, and the cast strip meanders in the pinch roll and the inline mill May be off-center on the entry side.

  The occurrence of the off-center of the cast strip on the inlet side of the in-line mill induces an asymmetry of the elongation rate in the width direction of the cast strip, resulting in a larger meandering, and the plate shape caused by the single elongation If a narrowing due to a defect or a single elongation occurs and the plate breaks or the meander becomes larger, there is a problem that the cast strip collides with the housing or the like and the plate breaks.

  As described above, at the start of casting, when changing from a plate profile (see FIGS. 11 (A) to 11 (C)) in which both end portions and center portions of the plate width have thicknesses to a substantially uniform plate profile, casting is performed. Various techniques for applying a stable tension to the strip at an early timing and starting a flying touch in an in-line mill at an early timing to suppress the occurrence of off-gauge are disclosed.

For example, a technique for detecting a meandering amount of a cast strip and adjusting a left-right gap difference in a pinch roll is disclosed (for example, refer to Patent Document 2).
In addition, a technique is disclosed in which a left-right load on a pinch roll is detected and a left-right load difference on the pinch roll is reduced to adjust a left-right gap difference on the pinch roll (see, for example, Patent Document 3). ).

  Also, by reducing the roll diameter at both ends in the width direction of the pinch roll corresponding to the plate end of the cast strip, the influence of changes in the plate profile of the cast strip is reduced from the start of casting until reaching steady casting. In order to do so, a technique for providing a pinch roll with a trapezoidal shape is disclosed (for example, see Patent Document 4).

JP 2000-343103 A Japanese Patent Laid-Open No. 2003-039108 Japanese Patent No. 4850829 JP 2012-170960 A

  However, in order to detect the meandering amount of the cast strip and adjust the difference between the left and right gaps in the pinch roll, it is necessary that the width of the cast strip is constant, and the cast strip has an asymmetric burr or the like. In some cases, it may be difficult to determine whether meandering is occurring or whether burr or the like is affecting. Further, when the threshold value of the meandering control is set to be large, there is a problem that the response property of the meandering control is lowered.

  In addition, the meandering control needs to be executed based on the measured meandering amount, but even if meandering occurs, the meandering control cannot be reflected until the meandering amount is measured by the detector. There is a problem that it cannot be adjusted in real time.

On the other hand, if the cast strip does not meander and off-center occurs, or if there is a temperature difference between the left and right ends of the cast strip, the left and right load on the pinch roll is adjusted by adjusting the left and right gap difference in the pinch roll. Even if the difference is eliminated, there is a problem that the meandering does not necessarily decrease.
Further, when off-center occurs when the casting strip is not meandering, there is a problem that meandering is promoted by reducing the roll diameter of the portion corresponding to the plate end of the casting strip.

  This invention is made | formed in view of such a subject, and suppresses meandering in an in-line mill, when the thin-walled slab cast with the twin drum type thin-wall slab continuous casting apparatus is sent to an in-line mill and rolled. An object of the present invention is to provide a pinch roll device before rolling and a pinch roll method before rolling.

  Therefore, the inventors of the present invention suppress the meandering in the in-line mill and stably roll the thin-walled slab cast by the twin-drum type thin-wall slab continuous casting apparatus to the in-line mill for rolling. As a result of earnestly researching the technology, the gap formed by the pair of pinch rolls constituting the pinch roll before rolling is changed in correspondence with the plate profile of the thin cast slab that changes with the elapsed time after the start of casting. In order to prevent partial rolling of thin cast slabs even when a high pressing force is applied, to pass thin cast slabs in-line stably without meandering or plate shape defects, and to accelerate the timing of flying touch The knowledge that it is effective was obtained.

In order to solve the above problems, the present invention proposes the following means.
According to the first aspect of the present invention, a molten metal storage section is formed by a pair of cooling drums and side weirs, and the molten metal stored in the molten metal storage section is rotated on the peripheral surface while rotating the pair of cooling drums. A pinch roll device before rolling, in which a thin slab formed in a twin drum thin slab continuous casting device for solidification, growth and casting is sent to an in-line mill by a pair of pinch rolls, the pair of pinch rolls rotating The first convex curve shape in which the inclination of the tangent to the rotation axis gradually increases while being reduced in diameter from one side of the axis toward the other side, and the first convex curve shape connected to the first convex curve shape and contracted toward the other side. A first profile including a first curved shape having a first concave curved shape having a tangential inclination with respect to the rotational axis gradually decreasing while being diameter-formed is formed on the outer peripheral surface. The first pinch roll thus formed is connected to the second concave curve shape in which the diameter of the tangent line with respect to the rotation axis gradually increases while increasing in diameter from one side to the other side of the rotation axis. And a second profile including a second convex curve shape having a second convex curve shape having a tangential slope with respect to the rotation axis gradually decreasing while being increased in diameter toward the other side. A pinch roll, wherein the first pinch roll and the second pinch roll are configured to be relatively movable along the rotation axis.

  According to the seventh aspect of the present invention, a molten metal storage section is formed by a pair of cooling drums and side weirs, and the molten metal stored in the molten metal storage section is rotated on the peripheral surface while rotating the pair of cooling drums. A pinch roll method before rolling, in which a thin slab formed in a twin drum type thin slab continuous casting apparatus for solidification, growth and casting is sent to an in-line mill by a pair of pinch rolls, the pair of pinch rolls having a rotation axis The first convex curve shape in which the diameter of the tangent to the rotation axis gradually increases while being reduced in diameter as it goes from one side to the other side, and the diameter is reduced as it is connected to the first convex curve shape and toward the other side However, a first profile including a first curved shape having a first concave curved shape in which the inclination of the tangent to the rotational axis gradually decreases is formed on the outer peripheral surface. In addition, the first pinch roll is connected to the second concave curve shape in which the diameter of the tangential line with respect to the rotation axis gradually increases while increasing in diameter from one side to the other side of the rotation axis. A second pinch having a second profile including a second convex curve shape having a second convex curve shape having a tangential inclination with respect to the rotation axis gradually decreasing while increasing in diameter toward the other side. A second pinch roll having a second profile including a second curved shape formed on an outer peripheral surface, and the first pinch roll and the second pinch roll are relative to each other along the rotation axis. It is configured to be movable.

According to the pre-rolling pinch roll device and the pre-rolling pinch roll method according to the present invention, the thin cast slab cast by the twin-drum type thin cast continuous casting device has a first convex curve shape and a first concave curve shape. The first profile including the first curved shape having the first curved shape and the second profile including the second curved shape having the second concave curved shape and the second convex curved shape on the outer peripheral surface. A pair of pinch rolls provided with the formed second pinch roll is used to send to the in-line mill, so that the gap between the thin cast pieces formed by the pair of pinch rolls is cast after the casting starts. It is possible to efficiently cope with the unevenness of the plate profile of the thin cast slab until it is reached, and as a result, the reduction of the thin cast slab in the pinch roll before rolling can be suppressed.
As a result, the thin cast slab can be efficiently fed to an in-line mill and efficiently rolled.

In this specification, the first convex curve shape, the first concave curve shape, the first curve shape, the second convex curve shape, the second concave curve shape, and the second curve shape are not defined by polynomials but other than polynomials. Means (for example, a set of numerical data).
In this specification, the first curve shape and the second curve shape may or may not be the same when the first curve shape defined from one side and the second curve shape defined from the other side are the same. It shall be.
Further, the first profile and the second profile are connected to one side of the first curve shape and the second curve shape (for example, connected to one side of the first convex curve shape and gradually expanded from one side to the other side. It may include a curved shape to be radiused, a curved shape that is connected to the other side of the second convex curved shape and gradually decreases in diameter from one side to the other side, and the like.
The relative movement of the first cooling drum and the second cooling drum is not only when both the first cooling drum and the second cooling drum move along the axis, but also between the first cooling drum and the second cooling drum. Only one of them may move along the axis.

  Invention of Claim 2 is the pinch roll apparatus before rolling of Claim 1, Comprising: At least any one of the said 1st curve shape and the said 2nd curve shape is defined with the polynomial expression It is characterized by.

  Invention of Claim 8 is the pinch roll method before rolling of Claim 7, Comprising: At least any one of the said 1st curve shape and the said 2nd curve shape is defined by the polynomial expression It is characterized by.

According to the pre-rolling pinch roll device and the pre-rolling pinch roll method according to the present invention, since a pair of pinch rolls in which at least one of the first curved shape and the second curved shape is defined by a polynomial is used, the first The curved shape and the second curved shape can be defined efficiently and reliably, and a pair of pinch rolls can be produced efficiently.
As a result, the manufacturing cost of the pair of pinch rolls can be reduced.

  In this specification, the fact that at least one of the first curve shape and the second curve shape is defined by a polynomial (for example, a third or higher order polynomial) means that both the first curve shape and the second curve shape are polynomials. In addition to the case where it is defined, the case where only one of the first curve shape and the second curve shape is defined by a polynomial is included.

  Invention of Claim 3 is the pinch roll apparatus before rolling of Claim 1 or 2, Comprising: It was connected to the said other side of the said 1st curve shape, and was diameter-reduced as it went to the said other side. At least one of a first edge relief shape and a second edge relief shape connected to the one side of the second curved shape and reduced in diameter toward the one side is provided.

  Invention of Claim 9 is the pinch roll method before rolling of Claim 7 or 8, Comprising: It was connected to the said other side of the said 1st curve shape, and was diameter-reduced as it went to the said other side. At least one of a first edge relief shape and a second edge relief shape connected to the one side of the second curved shape and reduced in diameter toward the one side is provided.

  According to the pre-rolling pinch roll device and the pre-rolling pinch roll method according to the present invention, since the pair of cooling drums includes at least one of the first edge relief shape and the second edge relief shape, casting starts. Even when a thick solidified shell is formed at the end of the thin slab, the occurrence of edge-up can be suppressed.

  In this specification, a pair of pinch rolls has at least one of the first edge relief shape and the second edge relief shape means that the pair of pinch rolls has both the first edge relief shape and the second edge relief shape. In addition to the case where it is provided, the pair of pinch rolls includes a case where only one of the first edge relief shape and the second edge relief shape is provided.

  Invention of Claim 4 is the pinch roll apparatus before rolling of any one of Claim 1 to 3, Comprising: In the board profile of the said thin slab with the elapsed time after the casting start acquired previously Based on this, the relative movement amount of the first pinch roll and the second pinch roll in the rotation axis direction is controlled.

  A tenth aspect of the present invention is the pre-rolling pinch roll method according to any one of the seventh to ninth aspects, wherein the sheet profile of the thin-walled slab with the elapsed time after the start of casting is acquired in advance. Based on this, the relative movement amount of the first pinch roll and the second pinch roll in the rotation axis direction is controlled.

  According to the pre-rolling pinch roll device and the pre-rolling pinch roll method according to the present invention, the axes of the first pinch roll and the second pinch roll are based on the plate profile of the thin-walled slab obtained in advance after the start of casting. Since the amount of relative movement in the direction is controlled, the thin cast can be stably fed to the in-line mill in correspondence with the uneven unevenness of the plate profile of the thin cast.

In this specification, acquiring the plate profile of a thin cast piece with the elapsed time after the start of casting in advance includes not only the case of obtaining by experiment, but also the case of obtaining by a method other than the experiment, such as simulation.
Also, when controlling the relative movement amount of the first pinch roll and the second pinch roll in the axial direction, when moving at a constant speed, when moving while changing the moving speed according to parameters such as the elapsed time after casting. Shall be included.

  Invention of Claim 5 is a pinch-roll apparatus before rolling of any one of Claim 1 to 4, Comprising: At least any one of the plate | board direction front of the said pair of pinch rolls, and the plate | board direction back. On the other hand, a position detection device that detects a position in the width direction of the thin cast piece is provided, and the pair of pinch rolls has a width of the thin cast piece based on the width direction position of the thin cast piece detected by the position detection device. The relative movement amount of the pair of pinch rolls is controlled so as to be sandwiched symmetrically with respect to the center in the direction.

  Invention of Claim 11 is the pinch roll method before rolling of any one of Claim 7 to 10, Comprising: At least any one of the plate | board direction front of said pair of pinch rolls, and the plate | board direction back. On the other hand, a position detection device that detects a position in the width direction of the thin cast piece is provided, and the pair of pinch rolls has a width of the thin cast piece based on the width direction position of the thin cast piece detected by the position detection device. The relative movement amount of the pair of pinch rolls is controlled so as to be sandwiched symmetrically with respect to the center in the direction.

  According to the pre-rolling pinch roll device and the pre-rolling pinch roll method according to the present invention, at the position in the width direction of the thin cast slab detected by the position detection device disposed at least one of the front in the plate passing direction and the rear in the plate passing direction. Based on this, the relative movement amount of the pair of pinch rolls is controlled so that the pair of pinch rolls are sandwiched symmetrically with respect to the center in the width direction of the thin cast piece, so that meandering caused by the load difference of the thin cast piece is suppressed. Can do.

  The invention according to claim 6 is the pre-rolling pinch roll device according to claim 5, wherein the pair of pinch rolls is configured so that moments generated on the left and right with respect to the center in the width direction of the thin cast slab are equal. The pressing force is controlled.

  The invention according to claim 12 is the pre-rolling pinch roll method according to claim 11, wherein the pair of pinch rolls are arranged so that the moments generated on the left and right with respect to the center in the width direction of the thin cast slab are equal. The pressing force is controlled.

  According to the pre-rolling pinch roll device and the pre-rolling pinch roll method according to the present invention, the pressing force of the pair of pinch rolls is controlled so that the moments generated on the left and right with respect to the center in the width direction of the thin cast slab are equal. The meandering due to the moment generated on the left and right with respect to the center in the width direction of the thin cast piece can be suppressed.

According to the twin-drum type thin cast piece continuous casting apparatus and the thin cast piece manufacturing method according to the present invention, the meandering generated in the thin cast piece is suppressed, and the time from the start of casting to the flying touch is shortened. A thin slab can be stably fed to an in-line mill.
As a result, the yield of thin-walled slabs in an in-line mill can be improved, and the production cost of thin-walled slabs can be reduced.

It is a figure explaining an example of schematic structure of a manufacturing process of a casting strip concerning a 1st embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining an example of schematic structure from a twin drum type cast strip continuous casting installation to an in-line mill which concerns on 1st Embodiment of this invention. It is a figure explaining an example of schematic structure of the pinch roll apparatus before rolling concerning a 1st embodiment of the present invention. It is a figure explaining an example of schematic structure of a pair of pinch roll concerning a 1st embodiment of the present invention. It is a figure which shows an example of the polynomial more than the 3rd order which comprises the 1st profile of the 1st pinch roll which concerns on 1st Embodiment of this invention. It is a conceptual diagram explaining the outline | summary at the time of the casting start at the time of manufacturing a cast strip by the twin drum type cast strip continuous casting equipment which concerns on 1st Embodiment of this invention. It is the schematic explaining the effect | action at the time of sending a casting strip to an in-line mill with the pinch roll apparatus before rolling which concerns on 1st Embodiment of this invention. It is a figure explaining an example of schematic structure of a pair of pinch roll concerning a 2nd embodiment of the present invention. It is a figure which shows an example of the 6th order polynomial which comprises the 1st profile of the 1st pinch roll which concerns on 2nd Embodiment of this invention. It is the schematic explaining the effect | action at the time of sending a casting strip to an in-line mill with the pinch roll apparatus before rolling which concerns on 2nd Embodiment of this invention. It is a conceptual diagram which shows the change with the elapsed time after the casting start of the profile of a cooling drum and the plate profile of a thin-walled slab at the time of manufacturing a casting strip by the conventional twin drum type thin-walled slab continuous casting apparatus. It is a conceptual diagram which shows the change of the plate profile of a thin slab produced by the temperature change until a cooling drum reaches steady state, when manufacturing a thin slab by a twin drum type thin slab continuous casting apparatus. It is a conceptual diagram which shows the plate profile of the thin slab at the time of casting start, when manufacturing a thin slab by the twin drum type thin slab continuous casting apparatus.

<First Embodiment>
The first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a diagram for explaining a schematic configuration of a manufacturing process of a cast strip (thin-walled slab), and FIG. It is a schematic block diagram explaining an example of a casting apparatus. FIG. 3 is a diagram illustrating a schematic configuration of the cooling drum according to the first embodiment.
1 and 2, reference numeral 1 denotes a casting strip manufacturing process, reference numeral 10 denotes a twin-drum type casting strip continuous casting facility, reference numeral R10 denotes a pair of cooling drums, and reference numeral S denotes a casting strip.

  As shown in FIG. 1, the cast strip manufacturing process 1 includes, for example, a tundish (storage device) T, a twin drum cast strip continuous casting facility 10, an antioxidant device 20, a cooling device 30, and a pinch before rolling. A roll device 40, an in-line mill 50, a post-rolling pinch roll device 60, and a winding device 70 are provided.

  The cast strip manufacturing process 1 includes tundish T, twin-drum type cast strip continuous casting equipment 10, antioxidant device 20, cooling device 30, pre-rolling pinch roll device 40, in-line mill 50, post-rolling pinch roll device 60, The winding device 70 is arranged in this order.

Further, a feed roll 81 is disposed between the twin drum cast strip continuous casting equipment 10 and the pinch roll device 40 before rolling.
A tension roll 82 is disposed between the pre-rolling pinch roll device 40 and the in-line mill 50, and a tension roll 83 is disposed between the in-line mill 50 and the post-rolling pinch roll device 60.
A deflector roll 84 is disposed between the pinch roll device 60 after rolling and the winding device 70.

  As shown in FIGS. 1 and 2, the twin-drum type casting strip continuous casting facility 10 includes, for example, a pair of cooling drums R10 and side weirs (not shown) disposed on both sides in the width direction of the pair of cooling drums R10. The pair of cooling drums R10 and the side weirs constitute the molten metal storage part 15.

The pair of cooling drums R10 includes a first cooling drum R11 and a second cooling drum R12, and the first cooling drum R11 and the second cooling drum R12 have a concave profile that is slightly recessed in the center in the width direction. ing.
The first cooling drum R11 and the second cooling drum R12 correspond to the plate thickness (internal quality) of the cast strip S to be manufactured, and the distance between the first cooling drum R11 and the second cooling drum R12 (the axis of the rotating shaft). Distance) is adjustable.

  The first cooling drum R11 and the second cooling drum R12 are configured such that a cooling medium (for example, cooling water) can be circulated therein and cooled by circulating the cooling medium therein. .

  In this embodiment, the first cooling drum R11 and the second cooling drum R12 are set such that, for example, the outer diameter is 800 mm, the drum body length (width) is 1500 mm, and the plate crown of the casting strip S in a steady state is 30 μm (initial Processed). Needless to say, the outer diameter and drum length (width) of the pair of cooling drums R10 are not limited to these.

  The antioxidant device 20 prevents the surface of the cast strip S immediately after casting from oxidizing and generating scale, and the oxygen amount is adjusted by, for example, nitrogen gas in the antioxidant device 20. ing. It is preferable to apply the antioxidant 20 as necessary in consideration of the steel type of the cast strip S to be cast.

On the downstream side of the twin drum cast strip continuous casting facility 10, the feed roll 81 clamps the cast strip S by a reduction device (not shown), and the loop of the cast strip S between the pair of cooling drums R 10 and the feed roll 81. While measuring the length, the rotational speed is controlled so that the loop length is constant, and a horizontal conveying force is applied to the casting strip S.
The feed roll 81 is constituted by a pair of rolls having a roll diameter of 200 mm and a roll trunk length (width) of 2000 mm, for example.

  The cooling device 30 includes, for example, a large number of spray nozzles (not shown), and cools the casting strip S by jetting cooling water from the spray nozzle to the surface (upper and lower surfaces) of the casting strip S according to the steel type. It is like that.

  As shown in FIG. 3, the pinch roll device 40 before rolling includes, for example, position detection devices 40A and 40B, an upper pinch roll (first pinch roll) R411, a lower pinch roll (second pinch roll) R412, and a housing. 41, roll chocks 42A and 42B, an upper rolling load detection device 43A, a lower rolling load detection device 43B, and an electric reduction device (reduction means) 44.

  The upper and lower pinch rolls R411 and R412 have hollow channels formed therein, and can be cooled by circulating a cooling medium (for example, cooling water). The upper and lower pinch rolls R411 and R412 have, for example, a roll diameter of 400 mm and a roll trunk length (width) of 2000 mm.

Further, as shown in FIG. 4A, the upper pinch roll R411 and the lower pinch roll R412 are controlled so as to move in the directions of arrows F411 and F412 along the drum width direction (axis lines O41 and O42).
The amount of movement of the upper pinch roll R411 and the lower pinch roll R412 is set based on, for example, the plate profile of the casting strip S that accompanies the elapsed time after the start of casting.

  Moreover, the moving amount | distance of upper pinch roll R411 and lower pinch roll R412 is set based on the plate profile of the casting strip S acquired by experiment, for example. In addition, you may set based on simulation not based on experiment, and it is good also as a structure controlled based on the data acquired by the board profile meter in real time by the movement amount of upper pinch roll R411 and lower pinch roll R412.

As shown in FIG. 4A, the upper pinch roll R411 is configured to be rotatable around an axis (rotation axis) O41, and a first profile PR411 is formed on the outer peripheral surface.
The first profile PR411 includes, for example, a first curved line shape D11. For example, the diameter of the tangential line with respect to the axis O41 gradually decreases as the diameter is once increased from the one side L to the other side R of the axis O41. Parallel to O41 and connected to the first curved line shape D11, the first curved line shape D11 is formed so that the inclination of the tangent to the axis O41 gradually increases while gradually increasing in diameter toward the other side R.
Here, the fact that the inclination with respect to the axis O41 increases or decreases is indicated by the absolute value of the inclination with respect to the axis O41.

The first curved line shape D11 is reduced in diameter as it goes from one side L to the other side R of the axis O41, and the slope of the tangent to the rotation axis O41 gradually increases, and the first convex curve shape D111. And the first concave curve shape D111 and the first concave curve shape D112 are provided with a first concave curve shape D111 and a first concave curve shape D112 that gradually decrease in diameter toward the other side R and gradually decrease in inclination of the tangent to the axis O41. The shape is gradually changed gradually.
Here, “the inclination of the tangential line with respect to the axis O41 gradually decreases while being reduced in diameter toward the other side R” of the axis O41 related to the first concave curve shape D112 means that the first concave curve shape D112 is an upper pinch. This is a set of tangents of a circle having the center of curvature outside the roll R411, and does not necessarily mean that the first concave curve shape D112 includes a portion that is recessed toward the axis O41.

As shown in FIG. 4A, the lower pinch roll R412 is configured to be rotatable around an axis (rotation axis) O42, and a second profile PR412 is formed on the outer peripheral surface.
The second profile PR412 includes, for example, a second curved line shape D12. The diameter of the tangential line with respect to the axis O42 gradually decreases as the diameter is once reduced from the one side L to the other side R of the axis O42, and the axis O42. Are connected to the second curved line shape D12, and the second curved line shape D12 is formed so that the inclination of the tangent line with respect to the axis O42 gradually increases while being gradually reduced in diameter toward the other side R.
Here, the fact that the inclination with respect to the axis O42 increases or decreases is indicated by the absolute value of the inclination with respect to the axis O42.

The second curved line shape D12 has a second concave curved line shape D121 and a second concave curved line shape D121 in which the diameter of the tangential line with respect to the rotational axis O42 gradually increases while the diameter is increased from one side L to the other side R of the axial line O42. And the second convex curve shape D122 and the second convex curve shape D122 are provided with a second convex curve shape D122 that gradually decreases in diameter toward the other side R and gradually decreases in inclination of the tangent to the axis O42. The shape is gradually changed gradually.
Here, according to the second concave curve shape D121, “the inclination of the tangential line with respect to the rotation axis O42 gradually increases as the diameter increases from one side L to the other side R of the axis O42”. D121 is the meaning of a set of tangents of a circle having the center of curvature outside the upper pinch roll R412 and does not necessarily mean that the second concave curve shape D121 is recessed toward the axis O42.

Hereinafter, referring to FIG. 4B, taking the first profile PR411 of the upper pinch roll R411 according to the first embodiment as an example, crowns of the upper pinch roll R411 and the lower pinch roll R412 (first profile PR411, second profile PR412). ). FIG. 4B is a diagram illustrating an example of a third-order polynomial and a fourth-order polynomial according to the first profile PR411 of the upper pinch roll R411.
As shown in FIG. 4B, the drive side end on one side L of the upper pinch roll R411 is set to 0, the work side end on the other side R is set to 1.0, and the crown at the center position (0.5) in the axial direction is set. Is described as 0.

In this embodiment, the first curve shape D11 and the second curve shape D12 can be defined by a third-order polynomial or a fourth-order polynomial (third-order or higher polynomial), as shown in FIG. 4B.
Further, a cubic or higher order polynomial defining the first curved line shape D11 from the one side L of the axis O41 toward the other side R, and the second curved line D12 defined from the other side R of the axis O42 toward the one side L. The third and higher order polynomials are the same.
A polynomial that defines the first curved line shape D11 from one side L of the axis O1 toward the other side R, and a polynomial that defines the second curved line shape D12 from the other side R in the direction of the axis O2 toward the one side L. May have different (not identical) configurations.

The crown (first profile PR411) of the upper pinch roll R411 is as shown in FIG. 4B.
FIG. 4B shows an example of a third-order or fourth-order polynomial constituting the crown of the upper pinch roll R411.
As for a specific method of obtaining the polynomial, the gap distribution in the axial direction between the upper pinch roll R411 and the lower pinch roll R412 in the state where the shift amount between the upper pinch roll R411 and the lower pinch roll R412 is maximized is shown in FIG. In the state where the profile of the thin cast slab at the start of casting as shown in (A) is geometrically coincident and the shift amount between the upper pinch roll R411 and the lower pinch roll R412 is minimized, the upper pinch The coefficient of each term is determined so that the axial gap distribution between the roll R411 and the lower pinch roll R412 is geometrically coincident with the profile of the thin cast slab at the steady state as shown in FIG. Also good.
The amount of thermal expansion in the radial direction of the first cooling drum R11 or the second cooling drum R12 may be obtained by heat conduction calculation, or by measuring the axial drum gap distribution before casting and in a steady state. You may ask.

<3rd order polynomial>
The crown of the upper pinch roll R411 can be represented by, for example, the following third order polynomial.
R13 (X) = A13 × X ³ + B13 × X ² + C13 × X + D13
A13 = 2472.8, B13 = 3118.3, C13 = 498.99,
D13 = 220.98
Here, R13 (X) represents the crown amount (numerical value per radius) from the axis O41, and X represents the position in the axial direction.

<4th order polynomial>
The crown of the upper pinch roll R411 can be represented by, for example, the following fourth-order polynomial.
R14 (X) = A14 × X ⁴ + B14 × X ³ + C14 × X ² + D14 × X + E14
A14 = 1544.3, B14 = 5561.4, C14 = 5048.7,
D14 = 885.06, E14 = 220.9875
Here, R14 (X) represents the crown amount (numerical value per radius) from the axis O41, and X represents the position in the axial direction.

In addition, the said polynomial is an example and can be arbitrarily set according to conditions.
Needless to say, it is easy to approximate the desired crown by setting the degree of the polynomial to higher order.

The upper and lower pinch rolls R411 and R412 are disposed in the housing 41 via roll chocks 42A and 42B, and are rotated by a motor (not shown).
Further, the upper pinch roll R411 is connected to the pass line adjusting device 44 via the upper rolling load detection device 43A, and the lower pinch roll R40B is connected to the reduction device 43B.

  When the rolling-down device 43 pushes up the lower pinch roll R412, the rolling load applied to the upper and lower pinch rolls R411 and R412 is detected, and a tension is generated between the pinch roll device 40 before rolling and the inline mill 50 in the casting strip S. It is like that.

The tension generated between the pre-rolling pinch roll device 40 and the in-line mill 50 is measured by a tension roll 82. And the speed of a pair of pinch roll R410 is controlled so that the tension | tensile_strength which arises between the pinch roll apparatus 40 before rolling and the inline mill 50 may become preset tension | tensile_strength.
Further, the pre-rolling pinch roll device 40 controls the pressing force of the pair of pinch rolls R412 so that the moments generated on the left and right with respect to the center in the width direction of the casting strip S are equal.

The in-line mill 50 is a device that rolls the cast strip S to reduce the cast strip S to a desired plate thickness. In this embodiment, the in-line mill 50 is a six-high rolling mill.
As shown in FIGS. 1 and 2, the in-line mill 50 includes work rolls 51A and 51B arranged opposite to each other, intermediate rolls 52A and 52B arranged behind the work rolls 51A and 51B, and intermediate rolls 52A and 52B. Backup rolls 53 </ b> A and 53 </ b> B arranged behind, an in-line mill control device 54, and a thickness gauge 55 are provided.

  The work rolls 51A and 51B are driven to rotate by a motor (not shown) and are cooled by cooling water from the entrance / exit side.

  The inline mill control device 54 includes a control unit 540, a hydraulic pressure reduction cylinder 541, a mill hydraulic pressure reduction device 542, a roll rotation speed setting means 543, a roll bending force setting means 544, and a roll cross angle setting means 545. Yes.

  Further, a hydraulic pressure reduction cylinder (hydraulic pressure reduction device) 541 is connected to the backup roll 53B, and a mill hydraulic pressure reduction device 542 is connected to the hydraulic pressure reduction cylinder 541 to control the hydraulic pressure reduction cylinder 541 according to an instruction from the control unit 540. The roll gap is adjusted.

  The roll rotation speed setting means 543, the roll bending force setting means 544, and the roll cross angle setting means 545 have a roll rotation speed, a roll bending force, and a roll cross angle with respect to the work rolls 51A and 51B and the backup rolls 53A and 53B. Is set.

The in-line mill 50 measures the plate thickness of the cast strip S with a plate thickness meter (for example, X-ray plate thickness) 55 disposed downstream, and the cast strip S is preset based on the measurement result. The roll gap is adjusted so as to form a thick plate.
In this embodiment, for example, the work roll outer diameter is 400 mm, the intermediate roll outer diameter is 450 mm, the backup roll outer diameter is 1200 mm, and the trunk length (width) is 2000 mm.

  The post-rolling pinch roll device 60 includes, for example, a pair of rolls that are vertically opposed to each other, a motor (motor) that drives the pinch roll, and a reduction device (hydraulic pressure) (not shown). The roll is squeezed to generate tension between the casting strip S and the in-line mill 50.

The tension between the in-line mill 50 and the post-rolling pinch roll device 60 is measured by the tension roll 83, and the speed of the second pinch roll is controlled so as to be a preset tension.
In addition, the roll of the pinch roll device 60 after rolling has an outer diameter of 400 mm and a roll body length (width) of 2000 mm, for example.

  The winding device 70 receives the cast strip S rolled by the in-line mill 50 and fed from the pinch roll device 60 after rolling through the deflector roll 84, and winds it in a coil shape.

Hereinafter, the production of the cast strip S in the cast strip production process 1 will be described.
(1) First, the tundish T temporarily stores the molten metal.
(2) Next, the molten metal stored in the tundish T is injected into the molten metal storage part 15 of the twin-drum type casting strip continuous casting equipment 10 through a nozzle formed in the lower part of the tundish. At this time, the amount of the molten metal stored in the molten metal storage unit 15 is made constant by controlling the nozzle.
(3) Next, while rotating the pair of cooling drums R10, the molten metal stored in the molten metal storage unit 15 is solidified and grown on the peripheral surfaces of the pair of cooling drums R10 to cast the casting strip S.
When casting is started in the twin-drum type casting strip continuous casting facility 10, for example, as shown in FIG. 5, the dummy sheet 11 is connected to a portion that becomes the tip of the casting strip S. At this time, a dummy bar 13 that is considerably thicker than the cast strip S is provided on the leading end side of the dummy sheet 11 in the traveling direction, and a projection thicker than the thickness of the cast strip S is formed at the connection portion of the cast strip S and the dummy sheet 11. Part 12 is formed.
In this embodiment, the dimensions of the cast strip S are, for example, a plate thickness of 2 mm and a plate width of 1200 mm, and the peripheral speed (casting speed) of the pair of cooling drums R10 is, for example, 150 m / min. However, it is not limited to this.
(4) The casting strip S formed by the pair of cooling drums R10 is subjected to an antioxidant treatment in the antioxidant device 20 as necessary.
(5) Next, the casting strip S is transported downstream by the feed roll 81 while keeping the loop length of the casting strip S between the cooling drum R10 and the feed roll 81 constant.
(6) Next, the casting strip S is cooled by the cooling device 30 as necessary.
(7) Next, the pre-rolling pinch roll device 40 sends the cast strip S to the in-line mill 50 while generating a tension between the pre-rolling pinch roll device 40 and the in-line mill 50.
(8) The inline mill 50 starts the flying touch after the protrusion 12 has passed through the inline mill 50. That is, the rolling force is applied while synchronizing the roll speed of the in-line mill with the plate speed of the casting strip S.
(9) The in-line mill 50 rolls the cast strip S and adjusts it to a desired plate thickness.
(10) The cast strip S is sent from the inline mill 50 to the winding device 70 while the tension between the inline mill 50 and the post-rolling pinch roll device 60 is generated in the cast strip S by the post-rolling pinch roll device 60.
(11) The winding device 70 winds the cast strip S that has been sent.

Next, with reference to FIG. 6, the operation when the casting strip S cast by the twin-drum type casting strip continuous casting equipment 10 is sent to the in-line mill 50 by the pre-rolling pinch roll device 40 will be described.
FIG. 6 is a schematic view for explaining the operation when the cast strip S is fed to the in-line mill 50 by the pinch roll device 40 before rolling.

(1) As shown in FIG. 6A, the upper pinch roll R411 and the lower pinch roll R412 are opposed to each other in the directions of the axes O41 and O42 (positions where the upper pinch roll R411 and the lower pinch roll R412 are aligned in the width direction). ).
The plate crown of the casting strip changes from a large convex crown immediately after the start of casting to a small convex crown at steady state (see FIG. 9).
When starting casting, the upper pinch roll R411 is moved in the direction of arrow F4111 and the lower pinch roll R412 is moved in the direction of arrow F4121. For example, the upper pinch roll R411 and the lower pinch roll R412 are separated from each other in the direction of the axes O41 and O42 by the first convex curve shape D111 and the second convex curve shape D122 (the first concave curve shape D112 and the second concave curve shape D121). Is stopped in the state of being close to each other in the directions of the axes O41 and O42. Here, the gap between the upper pinch roll R411 and the lower pinch roll R412 is arranged on the casting strip as much as possible so that the pressing force is uniform (any variation is reduced) at any position in the plate width direction.
(2) As shown in FIG. 6 (B), for example, in FIG. 6 (A), the first concave curve shape D112 and the second concave curve shape D121 are stopped in a state of being close to each other in the directions of the axes O41 and O42. The pinch roll R411 and the lower pinch roll R412 are moved in the directions of arrows F4112 and F4122.
At this time, the upper pinch roll R411 is concave in the direction of the axis O41, the lower pinch roll R412 is concave in the direction of the axis O42, and the gap between the pair of pinch rolls R410 is at the center of the axis O41 (O42). A gap is formed larger than the end (see FIG. 11).
Then, the upper pinch roll R411 and the lower pinch roll R412 are moved in the directions of the axis lines O41 and O42 according to the crown change of the cast strip S411 (S), and the pressing force is applied to the cast strip as evenly as possible in the plate width direction. To load.
(3) From the start of casting until reaching the steady casting, as shown in FIG. 6C, the upper pinch roll R411 is moved in the direction of arrow F4113 and the lower pinch roll R412 is moved in the direction of arrow F4123. Then, the casting strip S412 (S) is passed through.
As the upper pinch roll R411 and the lower pinch roll R412 move, the roll gap between the upper pinch roll R411 and the lower pinch roll R412 is smaller than that in FIG. It can cope with the change of the convex crown immediately after the start of casting.
During the period from the start of casting to the time of steady casting, the temperature of the first cooling drum R11 and the second cooling drum R12 (see FIG. 1) of the twin-drum type casting strip continuous casting equipment 10 rises, and the widthwise center side expands. Since the diameter (thermal expansion) causes the concave shape at the center in the width direction of the casting strip S412 (S) to be gradually smaller (shallow), the gap formed by the upper pinch roll R411 and the lower pinch roll R412 has a gap formed by the casting strip S412 ( Since it becomes narrow corresponding to S), the casting strip S412 (S) can be pressed and sandwiched evenly in the width direction.
(4) When the steady casting is reached, the movement of the upper pinch roll R411 and the lower pinch roll R412 is stopped as shown in FIG.
When reaching the steady casting, the plate profile of the casting strip S413 (S) does not change, so the upper pinch roll R411 and the lower pinch roll R412 are stopped.

According to the pre-rolling pinch roll device 40 and the pre-rolling pinch roll method according to the first embodiment, the first profile PR411 including the first curved shape D11 having the first convex curved shape D111 and the first concave curved shape D112 is provided. A pair of upper pinch rolls R411 formed and a pair of lower pinch rolls R412 formed with a second profile PR412 including a second curved shape D12 having a second concave curved shape D121 and a second convex curved shape D122. Since the casting strip S is sent to the in-line mill 50 using the pinch roll R410, the casting strip from when the gap between the casting strip S formed by the pair of pinch rolls R410 reaches the time of steady casting after the start of casting. It is possible to efficiently cope with changes in the sheet crown of the sheet profile of S. Reduction of the central convex portion of the cast strip S in the pinch roll device 40 (rolling) can be suppressed.
As a result, the cast strip S can be efficiently fed to the in-line mill 40 and efficiently rolled.

According to the pre-rolling pinch roll device 40 and the pre-rolling pinch roll method according to the first embodiment, a pair of pinch rolls R410 in which the first curved shape D11 and the second curved shape D12 are defined by a cubic polynomial is used. Therefore, the 1st curve shape D11 and the 2nd curve shape D12 can be defined efficiently and reliably, and a pair of pinch roll R410 can be manufactured efficiently.
As a result, the manufacturing cost of the pair of pinch rolls R410 can be reduced.

  According to the pre-rolling pinch roll device 40 and the pre-rolling pinch roll method according to the first embodiment, the first pinch roll R410 and the first pinch roll R410 and the first pinch roll R410 are obtained based on the plate profile of the casting strip S with the elapsed time after the start of casting. Since the relative movement amount of the 2-pinch roll R420 in the directions of the axes O41 and O42 is controlled, the casting strip S can be stably fed to the in-line mill 50 in correspondence with the unevenness of the plate profile of the casting strip S.

  According to the pre-rolling pinch roll device 40 and the pre-rolling pinch roll method according to the first embodiment, the position in the width direction of the casting strip S detected by the position detection devices 40A and 40B arranged forward in the plate passing direction and rear in the plate passing direction. Therefore, the relative movement amount of the pair of pinch rolls R410 is controlled so that the pair of pinch rolls R410 sandwich the casting strip S symmetrically in the center in the width direction, so that meandering due to the load difference of the casting strips S is suppressed. be able to.

  According to the pre-rolling pinch roll device 40 and the pre-rolling pinch roll method according to the first embodiment, the pressing force of the pair of pinch rolls R410 so that the moments generated on the left and right with respect to the center in the width direction of the casting strip S are equal. Therefore, meandering caused by the moment generated on the left and right with respect to the center in the width direction of the casting strip S can be suppressed.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS. 1 to 3, 5, 7 </ b> A, 7 </ b> B, and 8. Since FIGS. 1 to 3 and FIG. 5 are the same as those in the first embodiment, description thereof will be omitted. FIG. 7A is a diagram illustrating a schematic configuration of a pair of pinch rolls according to the second embodiment, and FIG. 7B is an example of a sixth-order polynomial (third-order or higher-order polynomial) according to the first profile of the upper pinch roll. FIG. 1-3, FIG. 7A, and FIG. 8, the code | symbol R420 has shown a pair of pinch roll.

As shown in FIG. 7A, the pair of pinch rolls R420 includes an upper pinch roll (first pinch roll) R421 and a lower pinch roll (second pinch roll) R422, and corresponds to the plate profile of the casting strip S, The distance between the upper pinch roll R421 and the lower pinch roll R422 (distance between the rotation axes) is adjusted.
Further, the upper pinch roll R421 and the lower pinch roll R422 can be controlled to move relative to each other in the directions of arrows F421 and F422 along the pinch roll width direction (axis lines O41 and O42).

As shown in FIG. 7A, the upper pinch roll R421 has a first profile PR421 formed on the outer peripheral surface thereof.
The first profile PR421 includes, for example, a first curved shape D21. For example, the diameter of the tangent line with respect to the axis O41 gradually decreases as the diameter is once increased from one side L to the other side R of the axis O41. To the first curved line shape D21, and a first edge relief shape E421 is formed on the other side R of the first curved line shape D21.
Here, the fact that the inclination with respect to the axis O41 increases or decreases is indicated by the absolute value of the inclination with respect to the axis O41.

The first curved line shape D21 has a first convex curved line shape D211 and a first convex curved line shape D211 in which the inclination of the tangential line with respect to the rotational axis O41 gradually increases while being reduced in diameter from the one side L to the other side R of the axis O41. And the first concave curve shape D211 and the first concave curve shape D212 are reduced in diameter toward the other side R while gradually decreasing the inclination of the tangent to the axis O41. The shape is gradually changed gradually.
Here, according to the first concave curve shape D212, "the inclination of the tangential line with respect to the axis O41 is gradually reduced while being reduced in diameter toward the other side R (of the axis O41)", the first concave curve shape D212 is It is a meaning of a set of tangents of a circle having the center of curvature outside the upper pinch roll R421, and does not necessarily mean that the first concave curve shape D212 includes a portion that is recessed toward the axis O41.

  The first edge relief shape E421 is connected to the other side R of the first convex curve shape D211, and is gradually reduced in diameter toward the other side R. In addition, it is preferable that the inclination of the first edge relief shape E421 with respect to the axis O41 gradually increases from the one side L toward the other side R.

As shown in FIG. 7A, the lower pinch roll R422 is configured to be rotatable around the axis O42, and a second profile PR422 is formed on the outer peripheral surface.
The second profile PR422 includes, for example, a second curved line shape D22, a second edge relief shape E422 is formed on one side L of the axis O42, and a second curve is formed on the other side R of the second edge relief shape E422. The shape D22 is connected, and the other side R of the second curved shape D22 is formed so that the inclination of the tangent to the axis O42 gradually increases while being gradually reduced in diameter.
Here, the fact that the inclination with respect to the axis O42 increases or decreases is indicated by the absolute value of the inclination with respect to the axis O42.

The second curved line shape D22 is enlarged in diameter from one side L to the other side R of the axis O42, and the slope of the tangent to the rotation axis O42 gradually increases, and the second concave curve shape D221. And the second convex curve shape D222 and the second convex curve shape D222 are formed such that the diameter of the tangential line with respect to the axis O42 gradually decreases while increasing in diameter toward the other side R. The shape is gradually changed gradually.
Here, according to the second concave curve shape D221, “the inclination of the tangential line with respect to the rotation axis O42 gradually increases as the diameter increases from one side L to the other side R of the axis O42”. D221 is the meaning of a set of tangents of a circle having the center of curvature outside the upper pinch roll R422, and does not necessarily mean that the second concave curve shape D221 is recessed toward the axis O42.

  The second edge relief shape E422 is connected to one side L of the second convex curve shape D221, and is gradually reduced in diameter toward the one side. In addition, it is preferable that the second edge relief shape E422 has a gradually decreasing inclination with respect to the axis O42 from the one side L toward the other side R.

In this embodiment, each of the first curve shape D21 and the second curve shape D22 is a curve that can be defined by a sixth-order polynomial (third-order or higher polynomial), and the first curve shape D21 is the axis O41. The 6th order polynomial defined from the one side L toward the other side R is the same as the 6th order polynomial defining the second curved line shape D22 from the other side R in the direction of the axis O42 toward the one side L. .
A polynomial that defines the first curved line shape D21 from one side L to the other side R of the axis O41 and a polynomial that defines the second curved line shape D22 from the other side R to the one side L of the axis O42. The configurations may be different (not identical).

Hereinafter, referring to FIG. 7B, taking the first profile PR421 of the upper pinch roll R421 according to the second embodiment as an example, the crowns of the upper pinch roll R421 and the lower pinch roll R422 (first profile PR421, second profile PR422). ). FIG. 7B is a diagram illustrating an example of a sixth-order polynomial according to the first profile PR421 of the upper pinch roll R421.
As shown in FIG. 7B, the drive side end on one side L of the upper pinch roll R421 is set to 0, the work side end on the other side R is set to 1.0, and the crown at the axial center position (0.5) is set. Is described as 0.

In this embodiment, the first curve shape D21 and the second curve shape D22 can be defined by a 6th order polynomial (third order or higher order polynomial) as shown in FIG. 7B.
Further, a sixth-order polynomial defining the first curved line shape D21 from one side L of the axis O41 to the other side R, and a sixth-order polynomial defining the second curved line shape D22 from the other side R of the axis O42 to the one side L. Are the same.

The crown (first profile PR421) of the upper pinch roll R421 is as shown in FIG. 7B.
FIG. 7B shows an example of a sixth-order polynomial constituting the crown of the upper pinch roll R421.

<6th order polynomial>
R26 (X) = A26 × X ⁶ + B26 × X ⁵ + C26 × X ³ + D26 × X ² + E26 × X + F26
A26 = 19118, B26 = 64084, C26 = 75507, D26 = 4343.6, E26 = 164.19, F26 = 260.84875
Here, R26 (X) represents the crown amount (numerical value per radius) from the axis O41, and X represents the position in the axial direction.

As for a specific method of obtaining the polynomial, the gap distribution in the axial direction between the upper pinch roll R421 and the lower pinch roll R422 in the state where the shift amount between the upper pinch roll R421 and the lower pinch roll R422 is maximized is shown in FIG. In the state where the profile of the thin slab at the start of casting as shown in (A) is geometrically coincident and the shift amount between the upper pinch roll R421 and the lower pinch roll R422 is minimized, the upper pinch The coefficient of each term is determined so that the axial gap distribution between the roll R421 and the lower pinch roll R422 geometrically matches the profile of the thin cast slab at the steady state as shown in FIG. Also good.
In addition, the said polynomial is an example and can be arbitrarily set according to conditions.
Needless to say, it is easy to approximate the desired crown by setting the degree of the polynomial to higher order.

Next, with reference to FIG. 8, the operation | movement at the time of sending the casting strip S which the twin drum type casting strip continuous casting installation 10 cast to the in-line mill 50 with the pinch roll apparatus 40 before rolling is demonstrated.
FIG. 8 is a schematic diagram for explaining the operation when the casting strip S is fed to the in-line mill 50 by the pre-rolling pinch roll device 40 according to the second embodiment. Note that description of the same parts as those in the first embodiment is omitted.

(1) Before the start of casting, as shown in FIG. 8A, the upper pinch roll R421 and the lower pinch roll R422 are opposed to each other in the directions of the axes O41 and O42 (the upper pinch roll R421 and the lower pinch roll R422 are (Position aligned in the width direction).
When starting casting, the upper pinch roll R421 is moved in the direction of arrow F4211, the lower pinch roll R422 is moved in the direction of arrow F4221, and, for example, the upper pinch roll R421 and the lower pinch roll R422 are formed in the first concave curve shape. D212 and the second concave curve shape D221 are stopped in a state in which they are close to each other in the directions of the axes O41 and O42. Here, the gap between the upper pinch roll R421 and the lower pinch roll R422 is arranged on the casting strip as much as possible so that the pressing force is uniform at any position in the plate width direction (so that variation is reduced).
(2) As shown in FIG. 8B, for example, in FIG. 8A, the first convex curve shape D211 and the second convex curve shape D222 are separated in the directions of the axes O41 and O42 (first concave curve shape D212). The upper pinch roll R421 and the lower pinch roll R422 stopped in a state where the second concave curve shape D221 is close to the axis lines O41 and O42 are moved in the directions of arrows F4212 and F4222.
And molten steel (metal molten metal) is supplied to a molten metal storage part, and a casting strip is formed.
At this time, the casting strip S421 (S) has a plate profile slightly depressed in the center in the width direction, but the pair of pinch rolls R420 is formed by replacing the recessed portion of the casting strip S421 (S) with another portion. Pass through with almost equal pressing force. Further, even if a large solidified shell is formed at the plate width end of the cast strip S421 (S), the first edge relief shape E421 and the second edge relief shape E422 have a large pressing force on the solidified shell portion (edge up portion). It is suppressed that the pressure is reduced.
After starting casting, the upper pinch roll R421 is moved in the direction of arrow F4212 and the lower pinch roll R422 is moved in the direction of arrow F4222 until the steady state is reached.
(3) From the start of casting until reaching the steady casting, as shown in FIG. 8C, the upper pinch roll R421 is moved in the direction of arrow F4213 and the lower pinch roll R422 is moved in the direction of arrow F4223. Then, the casting strip S12 is passed through.
During the period from the start of casting to the time of steady casting, the temperature of the first cooling drum R11 and the second cooling drum R12 (see FIG. 1) of the twin-drum type casting strip continuous casting equipment 10 rises, and the widthwise center side expands. Due to the diameter (thermal expansion), the concave shape at the center in the width direction of the casting strip S422 (S) is gradually reduced (shallow), but the gap formed by the upper pinch roll R421 and the lower pinch roll R422 is formed by the casting strip S422 ( Since it becomes narrow corresponding to S), the casting strip S422 (S) can be pressed and sandwiched evenly in the width direction.
When the edge up disappears (or the edge up falls below the set value) and the first edge relief shape E421 and the second edge relief shape E422 become unnecessary, the movement in the direction of the axis O41 (O42) is stopped.
(4) When reaching the steady casting, the movement of the upper pinch roll R421 and the lower pinch roll R422 is stopped as shown in FIG. 8 (D).
Since the plate profile of the casting strip S423 (S) does not change when reaching the steady casting, the upper pinch roll R421 and the lower pinch roll R422 are stopped, and the casting strip S423 (S) is pressed almost evenly in the width direction. While passing through.

According to the pinch roll device before rolling and the pinch roll method according to the second embodiment, the same effects as those of the first embodiment can be obtained.
In addition, since the pair of pinch rolls R420 includes the first edge relief shape E421 and the second edge relief shape E422, when a thick solidified shell is formed at the plate width end of the casting strip S at the start of casting. Even if it exists, it can suppress that the board width end part of the casting strip S is pressed with a big force, and is reduced (rolled).

Examples of the present invention will be described below.
The example was implemented in the manufacturing process of the casting strip provided with the structure similar to FIG. The cast strip used in the examples has a plate thickness of 2 mm and a plate width of 1200 mm.
The acceleration rate of the cooling drum from the start of casting is 150 m / min / 30 seconds, and the rotation speed of the cooling drum in the steady casting state is 150 m / min.
In the in-line mill, rolling with a reduction rate of 30% is performed, and the thickness of the cast strip on the exit side of the in-line mill is 1.4 mm.
The tension between the first pinch roll and the in-line mill is 3.6 tf (stress: about 15 MPa) as a resultant force. Further, the pressing force is about 15 tf in total.

In Comparative Example 1, in the pinch roll apparatus before rolling according to the prior art, the roll profile was set to be flat and the off-center of the cast strip was made zero.
Then, the load was controlled so that the pressing force was constant (right 7.5 tf, left 7.5 tf).

Comparative Example 2 was a pinch roll apparatus before rolling according to the prior art, in which the roll profile was set to a trapezoid and off-center (10 to 120 mm) was given to the cast strip.
Then, the load was controlled so that the pressing force was constant (right 7.5 tf, left 7.5 tf).

In Example 1 of the present invention, the off-center of the cast strip was made zero by using the pre-rolling pinch roll device provided with the roll profile according to the second embodiment.
Then, immediately after the start of casting, the end of the plate and the pinch roll are not in contact with each other, and in the steady state after the start of casting, the amount of shift of the pinch rolls in the directions of the axes O41 and O42 so that the pinch roll is in contact with the entire plate. The load was controlled so that the pressing force was constant (right 7.5 tf, left 7.5 tf).

Inventive Example 2 provided an off-center (10 to 120 mm) using a pre-rolling pinch roll device provided with the roll profile according to the second embodiment.
Then, immediately after the start of casting, the plate end portion and the pinch roll are not in contact with each other, and in a steady state after the start of casting, the pinch roll is in contact with the entire surface of the plate, and the amount of shift of the pinch roll in the directions of the axes O41 and O42 The load was controlled so that the pressing force was constant (right 7.5 tf, left 7.5 tf).
Further, the off-center position of the casting strip is detected, and the upper pinch roll and the lower pinch roll are equidistant from the center in the width direction of the casting strip in the axis O41 (O42) direction (symmetric with respect to the center in the width direction of the casting strip). ), The positions of the upper and lower pinch rolls in the direction of the axis O41 (O42) are corrected, and the left and right pinch roll pressing forces are corrected so that the pressing force is uniform in the plate width direction.

  In Comparative Example 1, a stable flying touch was not possible unless it was 28 seconds after the start of casting. As a result, an off gauge of about 40 m was generated.

  In Comparative Example 2, a stable flying touch became possible in 5 seconds from the start of casting, and the off gauge was suppressed to about 8 m. However, when the off-center is given 50 mm or more, the meandering expands, and finally the cast strip hits the housing post of the pinch roll device before rolling and breaks.

In Example 1 of the present invention, a stable flying touch was possible in 5 seconds from the start of casting, and the off gauge was suppressed to about 8 m.
In addition, the meandering was not expanded even when the off-center was given 50 mm, but if the off-center was given 90 mm or more, the meandering was enlarged, and finally the cast strip hit the housing post of the pinch roll device before rolling and broke. did.

In Example 2 of the present invention, a stable flying touch became possible in 5 seconds from the start of casting, and the off gauge was suppressed to about 8 m.
Further, the meandering was not enlarged even when 90 mm off-center was given.

From the above, according to the present invention, in the twin drum type thin cast strip continuous casting equipment, meandering in the pinch roll device before rolling is prevented, early flying touch is possible, and the cast strip can be manufactured stably. There was found.
As a result, it has become clear that the manufacturing cost of the cast strip can be reduced.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above-described embodiment, the case where the pair of pinch rolls R410 and R420 has a profile including the first curve shape and the second curve shape defined by a third-order or higher polynomial has been described. In the case where the profile formed on the surface of the pinch rolls R410 and R420 is defined by a polynomial, the order of the polynomial may be arbitrarily set.

  In the above-described embodiment, for example, the case where the first curved line shapes D11 and D21 and the second convex curved line shapes D21 and D22 are defined by a third-order or higher order polynomial has been described. It may be defined by a set of numerical data). Moreover, you may define any one of a 1st convex curve shape, a 1st concave curve shape, a 2nd concave curve shape, and a 2nd curve shape other than a polynomial.

  Moreover, in the said embodiment, regarding 1st curve shape D411, D421 and 2nd curve shape D412, D422, 1st curve shape D411, D421 defined from one side and 2nd curve shape D412 defined from the other side, Although the case where D422 is the same has been described, whether or not the first curve shapes D411 and D421 defined from one side are the same as the second curve shapes D412 and D422 defined from the other side is arbitrarily set. be able to.

  In the above embodiment, the case where the upper pinch rolls R421 and R421 and the lower pinch rolls R421 and R422 move together has been described. However, any one of the upper pinch rolls R421 and R421 and the lower pinch rolls R421 and R422 moves. This can be arbitrarily set, and only one of the upper pinch rolls R421 and R421 and the lower pinch rolls R421 and R422 may move along the axes O42 and O42.

  In the above-described embodiment, the case where the twin-drum type casting strip continuous casting apparatus 10 uses the dummy sheet 11 when starting casting of the casting strip S has been described, but this is the case where the dummy sheet is not used. However, the present invention can be applied to a twin-drum type casting strip continuous casting apparatus in which the profile of a pair of cooling drums thermally expands with time.

  Moreover, in the said embodiment, although the case where 1st profile PR421 and 2nd profile PR422 were equipped with 1st edge relief shape E421 and 2nd edge relief shape E422 was demonstrated, 1st profile PR421, 2nd, for example Whether or not the profile PR422 includes the first edge relief shape E421 and the second edge relief shape E422 can be arbitrarily set, and any one of the first profile PR421 and the second profile PR422 is the first edge relief shape E421, It is good also as a structure provided with the 2nd edge relief shape E422.

  In the above-described embodiment, the diameter of the first profile PR421 is enlarged toward one side L toward the other side R, and the other side R of the second profile PR422 is directed toward the other side R. Although the case where it is provided with the part to be diameter-reduced was demonstrated, it can be set arbitrarily whether it is set as the structure which is provided with both of these or any one, or neither.

  Moreover, in the said embodiment, although the case where a molten metal was molten steel was demonstrated, you may apply to the twin drum type thin-walled slab continuous casting apparatus using molten metal other than molten steel, such as aluminum and copper.

  According to the pre-rolling pinch roll device and the pre-rolling pinch roll method according to the present invention, the thin cast piece cast by the twin drum thin cast piece continuous casting device is passed through an in-line mill while suppressing meandering, and the thin wall Since the yield of slab can be improved, it is industrially applicable.

L One side R The other side O1, O2 Axis (cooling drum)
O42, O42 axis (rotation axis (pinch roll))
S Cast strip (thin slab)
T Tundish 10 Twin Drum Type Casting Strip Continuous Casting Equipment (Double Drum Type Thin Wall Casting Equipment)
R10 A pair of cooling drums R11 First cooling drum R12 Second cooling drum 11 Dummy sheet 12 Protruding portion 13 Dummy bar 15 Metal melt storage portion 20 Antioxidation device 30 Cooling device 40 Pinch roll devices 40A and 40B before rolling Position detection devices R421 and R421 Upper pinch roll (first pinch roll)
R421, R422 Lower pinch roll (second pinch roll)
PR11, PR21 First profile PR12, PR22 Second profile D11, D21 First curve shape D12, D22 Second curve shape D111, D211 First convex curve shape D112, D212 First concave curve shape E421 First edge relief shape D121, D221 Second convex curve shape D122, D222 Second concave curve shape E422 Second edge relief shape 42 Housing 42A, 42B Roll chock 43A Upper rolling load detection device 43B Lower rolling load detection device 44 Electric reduction device (reduction means)
50 In-line mills 51A, 51B Work rolls 52A, 52B Intermediate rolls 53A, 53B Backup roll 54 In-line mill controller 542 Hydraulic reduction cylinder 542 Mill hydraulic reduction apparatus 543 Roll rotation speed setting means 544 Roll bending force setting means 545 Roll cross angle setting means 55 Sheet thickness meter 60 Pinch roll device 81 after rolling Feed roll 82, 83 Tension roll 84 Deflector roll 70 Winding device

Claims (12)

A twin-drum type in which a molten metal reservoir is formed by a pair of cooling drums and side weirs, and the molten metal stored in the molten metal reservoir is solidified, grown and cast on the peripheral surface while rotating the pair of cooling drums A pinch roll device before rolling that sends a thin cast piece formed in a thin cast piece continuous casting device to an in-line mill by a pair of pinch rolls,
The pair of pinch rolls is
A first convex curve shape in which the inclination of a tangent to the rotation axis gradually increases while being reduced in diameter from one side of the rotation axis toward the other side, and connected to the first convex curve shape and toward the other side. A first pinch roll in which a first profile including a first curved shape having a first concave curved shape having a gradually decreasing inclination of a tangent to the rotation axis while being reduced in diameter is formed on the outer peripheral surface;
A second concave curve shape in which the diameter of the tangent line with respect to the rotation axis gradually increases while increasing in diameter from one side of the rotation axis toward the other side, and connected to the second concave curve shape and toward the other side. A second pinch roll in which a second profile including a second curved shape having a second convex curve shape having a gradually decreasing slope of a tangent to the rotation axis while being expanded in diameter is formed on the outer peripheral surface;
With
The pre-rolling pinch roll device, wherein the first pinch roll and the second pinch roll are configured to be relatively movable along the rotation axis. The pinch roll device before rolling according to claim 1,
At least one of the first curve shape and the second curve shape is defined by a polynomial, and the pinch roll device before rolling is characterized in that: The pre-rolling pinch roll device according to claim 1 or 2,
A first edge relief shape that is connected to the other side of the first curved shape and is reduced in diameter toward the other side, and is connected to the one side of the second curved shape and toward the one side. Therefore, the pinch roll device before rolling is provided with at least one of the second edge relief shapes reduced in diameter. A pre-rolling pinch roll device according to any one of claims 1 to 3,
The relative movement amount of the first pinch roll and the second pinch roll in the rotational axis direction is controlled based on the plate profile of the thin cast slab with the elapsed time after the start of casting acquired in advance. Pinch roll device before rolling. A pinch roll device before rolling according to any one of claims 1 to 4,
At least one of the pair of pinch rolls in the plate passing direction front and the plate passing direction rear is provided with a position detection device that detects the width direction position of the thin cast piece,
Based on the position in the width direction of the thin cast piece detected by the position detection device, the relative movement amount of the pair of pinch rolls is determined so that the pair of pinch rolls are sandwiched symmetrically with respect to the width direction center of the thin cast piece. A pinch roll device before rolling, characterized by controlling. It is a pinch roll device before rolling according to claim 5,
A pre-rolling pinch roll device, wherein the pressing force of the pair of pinch rolls is controlled so that moments generated on the left and right sides with respect to the center in the width direction of the thin cast slab are equal. A twin-drum type in which a molten metal reservoir is formed by a pair of cooling drums and side weirs, and the molten metal stored in the molten metal reservoir is solidified, grown and cast on the peripheral surface while rotating the pair of cooling drums A pinch roll method before rolling, in which a thin cast piece formed in a thin cast piece continuous casting apparatus is sent to an in-line mill by a pair of pinch rolls,
The pair of pinch rolls is
A first convex curve shape in which the inclination of a tangent to the rotation axis gradually increases while being reduced in diameter from one side of the rotation axis toward the other side, and connected to the first convex curve shape and toward the other side. A first pinch roll in which a first profile including a first curved shape having a first concave curved shape having a gradually decreasing inclination of a tangent to the rotation axis while being reduced in diameter is formed on the outer peripheral surface;
A second concave curve shape in which the diameter of the tangent line with respect to the rotation axis gradually increases while increasing in diameter from one side of the rotation axis toward the other side, and connected to the second concave curve shape and toward the other side. A second pinch roll in which a second profile including a second curved shape having a second convex curve shape having a gradually decreasing slope of a tangent to the rotation axis while being expanded in diameter is formed on the outer peripheral surface;
With
The pre-rolling pinch roll method, wherein the first pinch roll and the second pinch roll are configured to be relatively movable along the rotation axis. The pinch roll method before rolling according to claim 7,
A pinch roll method before rolling, wherein at least one of the first curved shape and the second curved shape is defined by a polynomial expression. The pinch roll method before rolling according to claim 7 or 8,
A first edge relief shape that is connected to the other side of the first curved shape and is reduced in diameter toward the other side, and is connected to the one side of the second curved shape and toward the one side. Therefore, the pinch roll method before rolling characterized by comprising at least one of the second edge relief shapes reduced in diameter. A pre-rolling pinch roll method according to any one of claims 7 to 9,
The relative movement amount of the first pinch roll and the second pinch roll in the rotational axis direction is controlled based on the plate profile of the thin cast slab with the elapsed time after the start of casting acquired in advance. Pinch roll method before rolling. It is the pinch roll method before rolling according to any one of claims 7 to 10,
At least one of the pair of pinch rolls in the plate passing direction front and the plate passing direction rear is provided with a position detection device that detects the width direction position of the thin cast piece,
Based on the position in the width direction of the thin cast piece detected by the position detection device, the relative movement amount of the pair of pinch rolls is determined so that the pair of pinch rolls are sandwiched symmetrically with respect to the width direction center of the thin cast piece. A pinch roll method before rolling characterized by controlling. The pre-rolling pinch roll method according to claim 11,
A pre-rolling pinch roll method, wherein the pressing force of the pair of pinch rolls is controlled so that the moments generated on the left and right sides of the thin cast slab are equal to each other in the width direction.

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