JP6759959B2 - Pre-rolling pinch roll device and pre-rolling pinch roll method - Google Patents

Description

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

As is well known, a pair of cooling drums for continuous casting (hereinafter referred to as cooling drums) are arranged in parallel, and the facing peripheral surfaces are rotated from above to downward, respectively, and hot water formed by the peripheral surfaces of these cooling drums is formed. Used by a twin-drum type casting strip continuous casting device that injects molten metal into the reservoir, cools and solidifies the molten metal on the peripheral surface of the cooling drum, and continuously casts thin-walled slabs (hereinafter referred to as casting strips). (See, for example, Patent Document 1).

As described in Patent Document 1, the twin-drum type casting strip continuous casting facility solidifies and grows the molten metal injected into the hot water pool on the peripheral surface of the cooling drum while rotating the cooling drum to form 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 the desired plate thickness by the in-line mill is coiled by a winding device installed downstream of the in-line mill.

The in-line mill described in Patent Document 1 is composed of, for example, a work roll which is a rolling roll provided so as to face each other across a casting strip, and a backup roll installed behind the work roll. Further, in the example described in Patent Document 1, the hydraulic reduction cylinder is installed in the housing located above the backup roll chock above the casting strip.

The hydraulic 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), and the reaction force from the casting strip 2 causes contact between the work roll and the casting strip. It is designed to detect. Further, a mill hydraulic reduction device is connected to the hydraulic reduction cylinder, and the mill hydraulic reduction device is connected to the overall control device.
Then, the mill hydraulic pressure reduction device can control the hydraulic pressure reduction cylinder to change the roll gap based on a command (mill reduction REF signal) from the integrated control device.

In the in-line mill, after the tip of the casting strip cast during steady casting has passed through the in-line mill, the roll gap is tightened while rotating the roll of the in-line mill to start rolling. The rolling method is called flying touch.

Further, in the twin-drum type thin-walled thin-walled casting strip continuous casting equipment, as shown in Patent Document 1 (FIG. 7), a dummy sheet is connected to the tip of the casting strip, the casting strip is pulled out, and casting is started.
Further, the dummy bar leading the dummy sheet is formed to be considerably thicker than the strip-shaped slab, and a protrusion thicker than the plate thickness of the casting strip is formed at the connection portion between the tip of the casting strip and the dummy sheet. ing.
Then, rolling (flying touch) in the in-line mill is started after the above-mentioned protrusions have passed through the in-line mill.

In a twin-drum thin-walled casting strip continuous casting facility, 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 rises due to contact with the molten metal.
Further, the cooling drum is cooled from the inner surface by a cooling medium (for example, cooling water) so as not to 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 during casting is called the steady temperature, and such a state is called the steady state.

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

FIG. 9 is a conceptual diagram showing changes with time after the start of casting of the profile of the cooling drum and the plate profile of the casting strip when the casting strip is manufactured by the conventional twin-drum casting strip continuous casting equipment. The plate profile of the casting strip shows a form before the cooling drum is cast without shifting and the reduction in the in-line mill is performed.

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

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

Then, after a further time has passed from the start of casting and the steady state is reached, the cooling drum R102 is further expanded (diameter expanded) by the heat input from the molten metal, as shown in FIG. 9C. It changes to R103, which is a slightly concave profile. Therefore, the plate profile of the casting strip S103 is changed to the casting strip S103, which has a convex shape with a crown amount smaller than that of the casting strip S102.

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

On the other hand, changes in the plate profile of the casting strip include changes due to thermal expansion of the cooling drum, as well as changes in the 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.

Generally, the stronger the cooling in the cooling drum, the thicker the solidified shell thickness and the thicker the cast strip. In the width direction of the cooling drum, the cooling efficiency is higher at the widthwise end of the cooling drum than at the center side of the cooling drum in the plate direction.

Therefore, the thickness of the solidified shell is thicker 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 portion becomes thicker than the plate thickness at the plate center portion, and the portion where the plate thickness at the plate end portion is thick is called edge-up. The amount of this edge-up is the largest at the start of casting, decreases with the elapsed time after the start of casting, and is almost eliminated at the time of steady casting.

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

Immediately after the start of casting, heat is more likely to escape at the widthwise end of the cooling drum than at the center of the cooling drum. Therefore, the molten metal is largely cooled at the widthwise end of the casting strip, and the solidified shell is formed at the casting strip. The width direction end portion is formed thicker than the width direction center portion.
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 formed 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 widthwise end of the cooling drum becomes smaller than at the start of casting, and in the molten metal, the cooling at the widthwise end of the casting strip is smaller than at the start of casting. Therefore, the difference in thickness between the central 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 after a while after the start of casting has an edge-up smaller than that of the casting strip S201 immediately after the start of casting at the end in the width direction.

After more time has passed from the start of casting and the steady state is reached, the temperature difference between the center side of the cooling drum and the widthwise end of the cooling drum becomes smaller, and the thickness of the solidification shell at the center and end of the width direction becomes smaller. There is almost no difference.
As a result, as shown in FIG. 10C, the edge-up of the plate profile of the casting strip S203 after a further time has passed from the start of casting and reached a steady state is almost eliminated.

The time from FIG. 10 (A) to reaching FIG. 10 (C) varies depending on the steel type (melting temperature) of the molten metal, the thickness of the casting strip, the rotation speed of the cooling drum, and the cooling efficiency, but is shown in FIG. 9 (A). ) ~ It is almost the same as the case of FIG. 9C, and it takes about 30 seconds from the start of casting.

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

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

Twin-drum type thin-walled casting strip When rolling a casting strip cast by a continuous casting facility with an in-line mill, the temperature of the casting strip is about 1000 ° C. on the in-line mill inlet side, so that the metal flow (width spread) in the plate width direction. However, the in-line mill does not have sufficient crown control capability to correspond to the cast strip of the plate profile as shown in FIG. 11 (A).

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

It is effective to increase the tension of the in-line mill for plate breakage due to drawing due to the medium 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 take a high pressing force of the pinch roll, and if the pressing force of the pinch roll is taken high, it is as shown in FIGS. 11 (A) and 11 (B). A portion with a thick plate may be rolled.

Then, if the thick portion is rolled, the plate breaks due to meandering with a pinch roll and the plate breaks due to drawing with an in-line mill due to severe shape defects. When the plate breaks, the remaining molten metal is immediately disposed of, which causes a great decrease in yield.

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

As described above, in order to start the flying touch in the in-line mill earlier and roll the cast strip to the desired plate thickness stably and efficiently, tension is applied to the cast strip on the inlet and outlet sides of the in-line mill. It is effective to load, and the larger the tension, the more effective it is to prevent meandering and shape defects. For that purpose, the pressing force of the pinch roll is increased and the pressing force of the pinch roll is increased to meander. It is effective not to cause poor shape or shape.

As described above, if the pressing force of the pinch roll is increased to lightly reduce the casting strip, the casting strip stretches asymmetrically in the width direction, and the casting strip meanders in the pinch roll to form an in-line mill. It may be off-center on the entrance side.

The occurrence of off-center of the casting strip on the inlet side of the in-line mill induces elongation asymmetry in the width direction of the casting strip, resulting in greater meandering and plate shape due to one-sided elongation. There is a problem that the cast strip collides with the housing or the like and the plate breaks when the drawing occurs due to the defect or the one-sided elongation and the plate breaks or the meandering becomes large.

As described above, when the plate profile (see FIGS. 11 (A) to 11 (C)) in which both ends and the center of the plate width are set to the plate thickness at the start of casting is changed to a nearly uniform plate profile, casting is performed. Various techniques have been disclosed 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.

For example, a technique for detecting the meandering amount of a cast strip and adjusting the difference between the left and right gaps in a pinch roll is disclosed (see, for example, Patent Document 2).
Further, a technique for adjusting the left-right gap difference in the pinch roll by detecting the left-right load in the pinch roll and reducing the left-right load difference in the pinch roll is disclosed (see, for example, Patent Document 3). ).

In addition, the roll diameter on both ends of the pinch roll corresponding to the plate end of the casting strip is reduced to reduce the influence of changes in the plate profile of the casting strip from the start of casting to the arrival of steady casting. To this end, a technique for imparting a trapezoidal shape to a pinch roll is disclosed (see, for example, Patent Document 4).

Japanese Unexamined Patent Publication No. 2000-343103 Japanese Unexamined Patent Publication No. 2003-039108 Japanese Patent No. 4850829 Japanese Unexamined Patent Publication No. 2012-170960

However, in order to detect the meandering amount of the casting strip and adjust the left-right gap difference in the pinch roll, it is necessary that the plate width of the casting strip is constant, and the casting strip has asymmetrical burrs and the like. If so, it may be difficult to determine whether meandering is occurring or burrs are affecting it. Further, if the threshold value of the meandering control is set large, there is a problem that the responsiveness of the meandering control is lowered.

In addition, it is necessary to execute meandering control based on the measured meandering amount, but even if meandering occurs, it cannot be reflected in the meandering control 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 casting strip does not meander and off-center occurs, or if there is a temperature difference between the left and right ends of the casting strip, adjust the left and right gap difference in the pinch roll to load the left and right sides of the pinch roll. There is a problem that even if the difference is eliminated, 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 portion of the casting strip.

The present invention has been made in view of such a problem, and suppresses meandering in an in-line mill when a thin-walled slab cast by a twin-drum type thin-walled slab continuous casting apparatus is sent to an in-line mill for rolling. It is an object of the present invention to provide a pre-rolling pinch-rolling apparatus and a pre-rolling pinch-rolling method capable.

Therefore, when the thin-walled slabs cast by the twin-drum type thin-walled slab continuous casting apparatus are sent to an in-line mill for rolling, the inventors of the present invention suppress meandering in the in-line mill and perform stable rolling. As a result of diligent research on the technology for this purpose, the gap formed by the pair of pinch rolls constituting the pre-rolling pinch roll is changed in correspondence with the plate profile of the thin-walled slab that changes with the elapsed time after the start of casting. To prevent partial rolling of thin-walled slabs even when a high pressing force is applied, to allow thin-walled slabs to pass through in-line stably without meandering or defective plate shape, and to accelerate the timing of flying touch. We obtained the finding that it is effective.

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 portion is formed by a pair of cooling drums and a side dam, and the molten metal stored in the molten metal storage portion is rotated on the peripheral surface of the pair of cooling drums. A pre-rolling pinch roll device that feeds thin-walled slabs formed in a double-drum type thin-walled slab continuous casting device that solidifies, grows, and casts to an in-line mill by a pair of pinch rolls, and the pair of pinch rolls rotate. a first convex curved shape absolute value of the tangent of inclination relative to the axis of rotation from one side of the axis while being reduced in diameter toward the other side is gradually increased, it is connected to the other side of the first convex curve shape A first profile including a first concave curve shape having a first concave curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually decreases while being reduced in diameter toward the other side is formed on the outer peripheral surface. The first pinch roll, the second concave curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually increases while the diameter is increased from one side to the other side of the rotation axis, and the second concave curve shape . A second profile including a second convex curve shape having a second convex curve shape connected to the other side and increasing in diameter toward the other side while the absolute value of the inclination of the tangent to the rotation axis gradually decreases. A second pinch roll formed on an outer peripheral surface thereof is provided, and the first pinch roll and the second pinch roll are configured to be relatively movable along the rotation axis.

According to the fourth aspect of the present invention, a molten metal storage portion is formed by a pair of cooling drums and a side dam, and the molten metal stored in the molten metal storage portion is rotated on the peripheral surface of the pair of cooling drums. A pre-rolling pinch roll method in which thin-walled slabs formed in a double-drum type thin-walled slab continuous casting apparatus that solidifies, grows, and casts are sent to an in-line mill by a pair of pinch rolls. The pair of pinch rolls is a rotation axis. while a first convex curved shape absolute value of the tangent slope is gradually increased with respect to the rotation axis while being reduced in diameter toward the other side from the side, is connected to the other side of the first convex curve shape wherein the A first profile including a first concave curve shape having a first concave curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually decreases while being reduced in diameter toward the other side is formed on the outer peripheral surface. A pinch roll, a second concave curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually increases while the diameter is increased from one side to the other side of the rotation axis, and the second concave curve shape . A second profile including a second convex curve shape having a second convex curve shape connected to the other side and increasing in diameter toward the other side while the absolute value of the inclination of the tangent to the rotation axis gradually decreases, is the outer circumference. A second pinch roll formed on a surface is provided, and the first pinch roll and the second pinch roll are configured to be relatively movable along the rotation axis.

According to the pre-rolling pinch-rolling apparatus and the pre-rolling pinch-rolling method according to the present invention, a thin-walled slab cast by a double-drum type thin-walled slab continuous casting apparatus is divided into a first convex curve shape and a first concave curve shape. A first pinch roll having a first profile including a first curved shape having a first curved shape is formed on an outer peripheral surface, and a second profile including a second curved shape having a second concave curve shape and a second convex curved shape is formed on the outer peripheral surface. Since a pair of pinch rolls provided with the formed second pinch roll is sent to the in-line mill, the gap between the thin-walled slabs formed by the pair of pinch rolls is a steady casting after the start of casting. It is possible to efficiently respond to changes in the unevenness of the plate profile of the thin-walled slab until it reaches the time, and as a result, it is possible to suppress the reduction of the thin-walled slab in the pinch roll before rolling.
As a result, thin-walled slabs can be efficiently sent to an in-line mill for efficient rolling.

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 defined by a polymorphism and other than the polymorphism. Means (eg, a set of numerical data, etc.) are included.
Further, in this specification, the first curve shape and the second curve shape may or may not be the same as the first curve shape defined from one side and the second curve shape defined from the other side. Suppose there is.
Further, the first profile and the second profile are connected to a shape portion other than the first curve shape and the second curve shape (for example, are connected to one side of the first convex curve shape and gradually expand from one side to the other side. It may include a curved shape to be calibrated, a curved shape connected to the other side of the second convex curve shape and gradually reduced in diameter from one side to the other side, and other shape portions).
Further, moving the first cooling drum and the second cooling drum relative to each other means that both the first cooling drum and the second cooling drum move along the axis line, and that the first cooling drum and the second cooling drum move relative to each other. It is assumed that only one of them may move along the axis.

The invention according to claim 2 is the pre-rolling pinch roll apparatus according to claim 1, wherein at least one of the first curved shape and the second curved shape is defined by a polynomial. It is characterized by.

The invention according to claim 5 is the pre-rolling pinch roll method according to claim 4 , wherein at least one of the first curve shape and the second curve shape is defined by a polynomial. It is characterized by.

According to the pre-rolling pinch roll device and the pre-rolling pinch roll method according to the present invention, 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 curved shape and the second curved shape can be defined efficiently and surely, and a pair of pinch rolls can be efficiently manufactured.
As a result, the manufacturing cost of the pair of pinch rolls can be reduced.

In this specification, when at least one of the first curve shape and the second curve shape is defined by a polynomial (for example, a polynomial of degree 3 or higher), both the first curve shape and the second curve shape are defined by a polynomial. 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.

The invention according to claim 3 is the pre-rolling pinch roll device according to claim 1 or 2, which is connected to the other side of the first curved shape and has a diameter reduced toward the other side. It is characterized by including 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.

The invention according to claim 6 is the pre-rolling pinch roll method according to claim 4 or 5 , which is connected to the other side of the first curved shape and has a diameter reduced toward the other side. It is characterized by including 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.

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 has at least one of a first edge relief shape and a second edge relief shape, casting is started. Even if a thick solidified shell is sometimes formed at the plate width end of the thin-walled slab, it is possible to suppress the occurrence of edge-up.

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

The invention according to claim 7 is the pre-rolling pinch roll method according to any one of claims 4 to 6 , wherein the thin-walled slab plate profile is obtained in advance with the elapsed time after the start of casting. Based on this, it is characterized in that 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 method according to the present invention, the relative movement amount of the first pinch roll and the second pinch roll in the axial direction is determined based on the plate profile of the thin-walled slab obtained in advance with the elapsed time after the start of casting. Since it is controlled, the thin-walled slab can be stably sent to the in-line mill in response to the unevenness of the plate profile of the thin-walled slab.

In this specification, obtaining the plate profile of a thin-walled slab in advance with the elapsed time after the start of casting includes not only the case of obtaining it by experiment but also the case of obtaining it by a method other than experiment such as simulation.
In addition, 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 movement speed according to parameters such as the elapsed time after casting. It shall include.

The invention according to claim 8 is the pre-rolling pinch roll method according to any one of claims 4 to 7 , wherein at least one of the pair of pinch rolls is forward in the plate-passing direction and rearward in the plate-passing direction. On the other hand, a position detecting device for detecting the position in the width direction of the thin-walled slab is provided, and the pair of pinch rolls are the width of the thin-walled slab based on the position in the width direction of the thin-walled slab detected by the position detecting device. It is characterized in that the relative movement amount of the pair of pinch rolls is controlled so as to be sandwiched symmetrically with respect to the center of the direction.

According to the pre-rolling pinch roll method according to the present invention, a pair of pinches are pinched based on the position in the width direction of the thin-walled slab detected by the position detecting device arranged at least one of the front in the plate-passing direction and the rear in the plate-passing direction. Since the relative movement amount of the pair of pinch rolls is controlled so that the rolls are symmetrically sandwiched with respect to the center of the thin-walled slab in the width direction, meandering due to the load difference of the thin-walled slab can be suppressed.

The invention according to claim 9 is the pre-rolling pinch roll method according to claim 8 , wherein the pair of pinch rolls have equal moments generated on the left and right sides with respect to the center in the width direction of the thin-walled slab. It is characterized by controlling the pressing force.

According to 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 sides are equal to the center in the width direction of the thin-walled slab. It is possible to suppress meandering caused by moments generated on the left and right with respect to the center of the direction.

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

It is a figure explaining an example of the schematic structure of the manufacturing process of the cast strip which concerns on 1st Embodiment of this invention. It is a figure explaining an example of the schematic structure from the twin drum type casting strip continuous casting equipment to the in-line mill which concerns on 1st Embodiment of this invention. It is a figure explaining an example of the schematic structure of the pre-rolling pinch roll apparatus which concerns on 1st Embodiment of this invention. It is a figure explaining an example of the schematic structure of the pair of pinch rolls which concerns on 1st Embodiment of this invention. It is a figure which shows an example of the polynomial of the third order or more which constitutes the 1st profile of the 1st pinch roll which concerns on 1st Embodiment of this invention. It is a conceptual diagram explaining the outline at the start of casting when the casting strip is manufactured by the twin drum type casting strip continuous casting equipment which concerns on 1st Embodiment of this invention. It is the schematic explaining the action when the cast strip is sent to an in-line mill by the pre-rolling pinch roll apparatus which concerns on 1st Embodiment of this invention. It is a figure explaining an example of the schematic structure of the pair of pinch rolls which concerns on 2nd Embodiment of this invention. It is a figure which shows an example of the 6th-order polynomial which constitutes the 1st profile of the 1st pinch roll which concerns on 2nd Embodiment of this invention. It is the schematic explaining the action when the cast strip is sent to an in-line mill by the pre-rolling pinch roll apparatus which concerns on 2nd Embodiment of this invention. It is a conceptual diagram which shows the change with the elapsed time after the start of casting of the profile of a cooling drum and the plate profile of a thin-walled slab when a casting strip is manufactured by a conventional double-drum type thin-walled slab continuous casting apparatus. FIG. 5 is a conceptual diagram showing a change in the plate profile of a thin-walled slab caused by a temperature change until the cooling drum reaches a steady temperature when a thin-walled slab is manufactured by a twin-drum type thin-walled slab continuous casting apparatus. It is a conceptual diagram which shows the plate profile of the thin-walled slab at the start of casting when the thin-walled slab is manufactured by the twin drum type thin-walled slab continuous casting apparatus.

<First Embodiment>
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. 1 to 6.
FIG. 1 is a diagram illustrating a schematic configuration of a manufacturing process of a casting strip (thin-walled slab), and FIG. 2 is a twin-drum type casting strip continuous casting facility (double-drum type thin-walled slab continuous) according to the first embodiment. It is a schematic block diagram explaining an example of a casting apparatus). Further, FIG. 3 is a diagram illustrating a schematic configuration of a cooling drum according to the first embodiment.
In FIGS. 1 and 2, reference numeral 1 indicates a casting strip manufacturing process, reference numeral 10 indicates a double-drum type casting strip continuous casting facility, reference numeral R10 indicates a pair of cooling drums, and reference numeral S indicates a casting strip.

As shown in FIG. 1, the casting strip manufacturing step 1 includes, for example, a tundish (storage device) T, a twin-drum casting strip continuous casting facility 10, an antioxidant device 20, a cooling device 30, and a pre-rolling pinch. It includes a roll device 40, an in-line mill 50, a post-rolling pinch roll device 60, and a take-up device 70.

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

Further, a feed roll 81 is arranged between the twin drum type casting strip continuous casting facility 10 and the pre-rolling pinch roll device 40.
Further, a tension roll 82 is arranged between the pre-rolling pinch roll device 40 and the in-line mill 50, and a tension roll 83 is arranged between the in-line mill 50 and the post-rolling pinch roll device 60.
Further, a deflector roll 84 is arranged between the pinch roll device 60 and the take-up device 70 after rolling.

As shown in FIGS. 1 and 2, the twin-drum casting strip continuous casting facility 10 includes, for example, a pair of cooling drums R10 and side weirs (not shown) arranged on both sides of the pair of cooling drums R10 in the width direction. The pair of cooling drums R10 and the side weir form the metal molten metal storage unit 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 with a slightly recessed center in the width direction. ing.
Further, in the first cooling drum R11 and the second cooling drum R12, the distance between the first cooling drum R11 and the second cooling drum R12 (the axis of the rotating shaft) corresponds to the plate thickness (internal quality) of the cast strip S to be manufactured. The distance) can be adjusted.

Further, the first cooling drum R11 and the second cooling drum R12 are configured so that a cooling medium (for example, cooling water) can be circulated inside and the cooling medium is circulated inside to be cooled. ..

In this embodiment, the first cooling drum R11 and the second cooling drum R12 are set so 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 the steady state is 30 μm (initial). Has been processed). Needless to say, the outer diameter and the drum body length (width) of the pair of cooling drums R10 are not limited to these.

The antioxidant device 20 prevents the surface of the casting strip S immediately after casting from being oxidized to generate scale, and in the antioxidant device 20, for example, the amount of oxygen is adjusted by nitrogen gas. ing. The antioxidant device 20 is preferably applied as necessary in consideration of the steel type of the casting strip S to be cast.

On the downstream side of the twin-drum casting strip continuous casting facility 10, the feed roll 81 sandwiches the casting strip S by a reduction device (not shown), and the loop of the casting strip S between the pair of cooling drums R10 and the feed roll 81. While measuring the length, the number of rotations is controlled so that the loop length becomes constant, and a horizontal conveying force is applied to the casting strip S.
The feed roll 81 is composed of, for example, a pair of rolls having a roll diameter of 200 mm and a roll body length (width) of 2000 mm.

The cooling device 30 is provided with, for example, a large number of spray nozzles (not shown), and cools the casting strip S by ejecting cooling water from the spray nozzles onto the surfaces (upper and lower surfaces) of the casting strip S depending on the steel type. It has become like.

As shown in FIG. 3, the pre-rolling pinch roll device 40 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. It includes 41, roll chocks 42A and 42B, an upper rolling load detecting device 43A, a lower rolling load detecting device 43B, and an electric rolling reduction device (reducing means) 44.

The upper and lower pinch rolls R411 and R412 have a hollow flow path formed inside, and can be cooled by flowing a cooling medium (for example, cooling water). Further, the upper and lower pinch rolls R411 and R412 have, for example, a roll diameter of 400 mm and a roll body length (width) of 2000 mm.

Further, the upper pinch roll R411 and the lower pinch roll R412 are controlled to move in the arrow F411 and F412 directions along the drum width direction (axis lines O41 and O42) as shown in FIG. 4A.
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 obtained in advance with the elapsed time after the start of casting.

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 obtained by an experiment. It should be noted that the setting may be made based on a simulation regardless of the experiment, or the movement amount of the upper pinch roll R411 and the lower pinch roll R412 may be controlled in real time based on the data acquired by the plate profile meter.

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

The first curve shape D11 has a first convex curve shape D111 and a first convex curve shape D111 in which the inclination of the tangent line with respect to the rotation axis O41 gradually increases while the diameter is reduced from one side L of the axis O41 toward the other side R. The first convex curve shape D111 and the first concave curve shape D112 are provided with a first concave curve shape D112 which is connected to and whose diameter is reduced toward the other side R and the slope of the tangent line with respect to the axis O41 gradually decreases. , It is set so that the shape gradually changes gradually.
Here, "the inclination of the tangent 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 pinched upward. It is intended to be a set of tangents of a circle having a center of curvature on the outside of the roll R411, and does not necessarily mean that the first concave curve shape D112 includes a portion recessed toward the axis O41.

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

The second curved shape D12 has a second concave curve shape D121 and a second concave curve shape D121 in which the inclination of the tangent line with respect to the rotating shaft O42 gradually increases while the diameter is increased from one side L of the axis O42 toward the other side R. The second convex curve shape D121 and the second convex curve shape D122 are provided with a second convex curve shape D122 in which the inclination of the tangent line with respect to the axis O42 gradually decreases while being connected to the other side R and increasing in diameter toward the other side R. , It is set so that the shape gradually changes gradually.
Here, according to the second concave curve shape D121, "the inclination of the tangent to the rotating shaft O42 gradually increases while the diameter is increased from one side L of the axis O42 toward the other side R" is the second concave curve shape. The purpose is that D121 is a set of tangents of a circle having a center of curvature on the outside of the upper pinch roll R412, and does not necessarily mean that the second concave curve shape D121 is recessed toward the axis O42.

Hereinafter, with reference to FIG. 4B, taking the first profile PR411 of the upper pinch roll R411 according to the first embodiment as an example, the crowns of the upper pinch roll R411 and the lower pinch roll R412 (first profile PR411, second profile PR412). ) Will be explained. FIG. 4B is a diagram showing 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 of one side L of the upper pinch roll R411 is set to 0, the work side end of the other side R is set to 1.0, and the crown at the central position (0.5) in the axial direction is set. Will be described as 0.

In this embodiment, the first curve shape D11 and the second curve shape D12 can be defined by a polynomial of degree 3 or a polynomial of degree 4 (polynomial of degree 3 or higher) as shown in FIG. 4B.
Further, a polynomial of degree 3 or higher that defines the first curve shape D11 from one side L of the axis O41 toward the other side R and a second curve shape D12 are defined from the other side R of the axis O42 toward one side L. The polynomials of degree 3 or higher are the same.
A polynomial that defines the first curve shape D11 from one side L of the axis O1 toward the other side R, and a polynomial that defines the second curve shape D12 from the other side R in the axis O2 direction toward one side L. May have different (non-identical) configurations.

The crown of the upper pinch roll R411 (first profile PR411) is as shown in FIG. 4B.
FIG. 4B shows an example of a third-order and fourth-order polynomial that constitutes the crown of the upper pinch roll R411.
Regarding the specific method of obtaining the polynomial, the axial gap distribution between the upper pinch roll R411 and the lower pinch roll R412 is shown in FIG. 9 in the state where the shift amount between the upper pinch roll R411 and the lower pinch roll R412 is maximized. An upper pinch is performed so as to geometrically match the profile of the thin-walled slab at the start of casting as shown in (A) and in a state where the shift amount between the upper pinch roll R411 and the lower pinch roll R412 is minimized. The coefficients of each term are determined so that the axial gap distribution between the roll R411 and the lower pinch roll R412 geometrically matches the profile of the thin-walled slab in a steady state as shown in FIG. 9 (C). Is 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 the start of casting and in the steady state. You may ask.

<3rd order polynomial>
The crown of the upper pinch roll R411 can be represented by, for example, a third-order polynomial as follows.
R13 (X) = A13 x X ³ + B13 x X ² + C13 x X + D13
A13 = 2472.8, B13 = 3118.3, C13 = 498.99,
D13 = 220.98
Here, R13 (X) indicates the amount of crown (numerical value per radius) from the axis O41, and X indicates 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 X ⁴ + B14 x X ³ + C14 x X ² + D14 x X + E14
A14 = 1544.3, B14 = 5561.4, C14 = 5048.7,
D14 = 885.06, E14 = 220.9875
Here, R14 (X) indicates the amount of crown (numerical value per radius) from the axis O41, and X indicates the position in the axial direction.

The above polynomial is an example, and can be arbitrarily set according to conditions and the like.
Further, it goes without saying that by setting the degree of the polynomial to a higher order, it becomes easier to approximate the desired crown.

Further, the upper and lower pinch rolls R411 and R412 are arranged in the housing 41 via the roll chock 42A and 42B, and are rotationally driven 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 detecting device 43A, and the lower pinch roll R40B is connected to the reducing device 43B.

When the reduction device 43 pushes up the lower pinch roll R412, the reduction load applied to the upper and lower pinch rolls R411 and R412 is detected, and tension is generated between the pre-rolling pinch roll device 40 and the in-line mill 50 in the casting strip S. It has become like.

Further, the tension generated between the pre-rolling pinch roll device 40 and the in-line mill 50 is measured by the tension roll 82. Then, the speed of the pair of pinch rolls R410 is controlled so that the tension generated between the pre-rolling pinch roll device 40 and the in-line mill 50 becomes a preset tension.
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 of the casting strip S in the width direction are equal.

The in-line mill 50 is an apparatus for rolling the casting strip S to thin the casting strip S to a desired plate thickness, and in this embodiment, it is a 6-stage rolling mill.
As shown in FIGS. 1 and 2, the in-line mill 50 includes work rolls 51A and 51B arranged to face each other, intermediate rolls 52A and 52B arranged behind the work rolls 51A and 51B, and intermediate rolls 52A and 52B. It is provided with backup rolls 53A and 53B arranged behind, an in-line mill control device 54, and a plate thickness meter 55.

The work rolls 51A and 51B are rotationally driven by a motor (not shown) and are cooled by cooling water from the inlet / outlet side.

The in-line mill control device 54 includes a control unit 540, a hydraulic reduction cylinder 541, a mill hydraulic 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. There is.

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

Further, 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 to be set.

Then, the in-line mill 50 measures the plate thickness of the casting strip S with a plate thickness gauge (for example, X-ray plate thickness) 55 arranged downstream, and the casting strip S is preset based on the measurement result. Adjust the roll gap so that it is formed to the thickness of the 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 body length (width) is 2000 mm.

The post-rolling pinch roll device 60 includes, for example, a pair of rolls arranged vertically facing each other, a motor (motor) for driving the pinch roll, and a reduction device (hydraulic) (not shown), and is pinched by the reduction device. The roll is rolled down to cause the casting strip S to generate tension with the inline 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 have a preset tension.
The roll of the pinch roll device 60 after rolling has, for example, an outer diameter of 400 mm and a roll body length (width) of 2000 mm.

The winding device 70 receives the cast strip S, which has been rolled by the in-line mill 50 and sent out from the pinch roll device 60 after rolling, via the deflector roll 84 and winds it into a coil.

Hereinafter, the production of the casting strip S in the casting strip manufacturing step 1 will be described.
(1) First, Tandish T temporarily stores the molten metal.
(2) Next, the molten metal stored in the tundish T is injected into the molten metal storage section 15 of the twin drum type casting strip continuous casting facility 10 via a nozzle formed in the lower part of the tundish. At this time, the nozzle is controlled to keep the amount of molten metal stored in the molten metal storage unit 15 constant.
(3) Next, while rotating the pair of cooling drums R10, the molten metal stored in the molten metal storage section 15 is solidified and grown on the peripheral surfaces of the pair of cooling drums R10 to cast the casting strip S.
When starting casting in the twin drum type casting strip continuous casting facility 10, for example, as shown in FIG. 5, a dummy sheet 11 is connected to a portion to be the tip of the casting strip S. At this time, a dummy bar 13 considerably thicker than the casting strip S is provided on the tip side of the dummy sheet 11 in the traveling direction, and a protrusion thicker than the thickness of the casting strip S is provided at the connection portion between the casting strip S and the dummy sheet 11. Part 12 is formed.
In this embodiment, the dimensions of the casting 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 cast 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 feed roll 81 conveys the cast strip S to the downstream side 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 needed.
(7) Next, the pre-rolling pinch roll device 40 sends the casting strip S to the in-line mill 50 while generating tension between the pre-rolling pinch roll device 40 and the in-line mill 50.
(8) The in-line mill 50 starts the flying touch after the protrusion 12 has passed through the in-line mill 50. That is, a 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 casting strip S to adjust the plate thickness to a desired value.
(10) The post-rolling pinch roll device 60 sends the casting strip S from the inline mill 50 to the winding device 70 while generating tension between the inline mill 50 and the post-rolling pinch roll device 60 on the casting strip S.
(11) The winding device 70 winds the sent casting strip S.

Next, with reference to FIG. 6, the operation when the casting strip S cast by the twin-drum casting strip continuous casting facility 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 illustrating an operation when the casting strip S is fed to the in-line mill 50 by the pre-rolling pinch roll device 40.

(1) As shown in FIG. 6A, the upper pinch roll R411 and the lower pinch roll R412 face each other in the axial directions O41 and O42 (the position where the upper pinch roll R411 and the lower pinch roll R412 are aligned in the width direction). ) Is placed.
The plate crown of the casting strip changes from a large convex crown immediately after the start of casting to a small convex crown in a 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 F4211. Then, for example, the upper pinch roll R411 and the lower pinch roll R412 are separated from each other by the first convex curve shape D111 and the second convex curve shape D122 in the axial directions O41 and O42 (the first concave curve shape D112 and the second concave curve shape D121). Are 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 equal at any position in the plate width direction (so that the variation is small).
(2) As shown in FIG. 6B, for example, in FIG. 6A, 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 axes O41 and O42 directions. The pinch roll R411 and the lower pinch roll R412 are moved in the directions of arrow F4112 and arrow F4122.
At this time, the upper pinch roll R411 is concave in the axis O41 direction, the lower pinch roll R412 is concave in the axis O42 direction, and the gap between the pair of pinch rolls R410 is centered in the axis O41 (O42) direction. 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 axes O41 and O42 directions according to the crown change of the casting strip S411 (S), and the pressing force is applied to the casting strip as evenly as possible in the plate width direction. Load.
(3) 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 from the start of casting until it reaches the time of steady casting. While passing through the casting strip S412 (S).
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 becomes smaller than that in FIG. 6B, although the gap at the center in the roll width direction is larger than the roll end. , It is possible to cope with the change and reduction of the convex crown immediately after the start of casting.
From the start of casting to the arrival at 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 casting strip continuous casting facility 10 rises and the center side in the width direction expands. As the diameter (thermal expansion) increases, the concave shape at the center of the casting strip S412 (S) in the width direction gradually becomes smaller (shallow), but the gap formed by the upper pinch roll R411 and the lower pinch roll R412 is formed by the casting strip S412 ( Since it becomes narrower corresponding to S), the cast strip S412 (S) can be pressed and sandwiched evenly in the width direction.
(4) When it reaches the time of steady casting, the movement of the upper pinch roll R411 and the lower pinch roll R412 is stopped as shown in FIG. 6 (D).
When it reaches during steady casting, the plate profile of the casting strip S413 (S) does not change, so that 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 curve shape D11 having the first convex curve shape D111 and the first concave curve shape D112 A pair of upper pinch rolls R411 formed and a lower pinch roll R412 formed with a second profile PR412 including a second curve shape D12 having a second concave curve shape D121 and a second convex curve shape D122. Since the casting strip S is sent to the in-line mill 50 by using the pinch roll R410, the casting strip from the start of casting to the time when the gap sandwiching the casting strip S formed by the pair of pinch rolls R410 reaches during steady casting. It is possible to efficiently respond to the change in the plate crown of the plate profile of S, and it is possible to suppress the reduction (rolling) of the central convex portion of the casting strip S in the pre-rolling pinch roll device 40.
As a result, the casting strip S can be efficiently sent to the in-line mill 40 for efficient rolling.

According to the pre-roll pinch roll device 40 and the pre-roll pinch roll method according to the first embodiment, a pair of pinch rolls R410 in which the first curve shape D11 and the second curve shape D12 are defined by a cubic polynomial are used. Therefore, the first curved shape D11 and the second curved shape D12 can be defined efficiently and surely, and the pair of pinch rolls R410 can be efficiently manufactured.
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 based on the plate profile of the casting strip S with the elapsed time after the start of casting obtained in advance. Since the relative movement amount of the 2-pinch roll R420 in the axes O41 and O42 directions is controlled, the casting strip S can be stably sent to the in-line mill 50 in response to 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 detecting devices 40A and 40B arranged in the front in the plate-passing direction and the rear in the plate-passing direction. Since the relative movement amount of the pair of pinch rolls R410 is controlled so that the pair of pinch rolls R410 symmetrically sandwich the casting strip S in the center in the width direction, the meandering caused by 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 is equal 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. Is controlled, so that the meandering caused by the moments generated on the left and right sides of the center of the casting strip S in the width direction can be suppressed.

<Second Embodiment>
Next, a second embodiment of the present invention will be described with reference to FIGS. 1 to 3, 5, 7A, 7B, and 8. Note that FIGS. 1 to 3 and 5 are the same as those in the first embodiment, and thus description thereof will be omitted. FIG. 7A is a diagram illustrating a schematic configuration of a pair of pinch rolls according to a second embodiment, and FIG. 7B is an example of a sixth-order polynomial (a third-order or higher polynomial) according to the first profile of the upper pinch roll. It is a figure which shows. In FIGS. 1 to 3, 7A and 8, reference numeral R420 indicates a pair of pinch rolls.

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 correspond 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 rotating shafts) is adjusted.
Further, the upper pinch roll R421 and the lower pinch roll R422 can be controlled to move relative to the 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, the first curved shape D21, and for example, the slope of the tangent line with respect to the axis O41 gradually decreases while the diameter is once increased from one side L of the axis O41 toward the other side R. Is connected to the first curved shape D21, and the first edge relief shape E421 is formed on the other side R of the first curved shape D21.
Here, increasing or decreasing the inclination with respect to the axis O41 is indicated by the absolute value of the inclination with respect to the axis O41.

The first curved shape D21 has a first convex curve shape D211 and a first convex curve shape D211 in which the inclination of the tangent line with respect to the rotating shaft O41 gradually increases while the diameter is reduced from one side L of the axis O41 toward the other side R. The first convex curve shape D211 and the first concave curve shape D212 are provided with a first concave curve shape D212 which is connected to and whose diameter is reduced toward the other side R and the slope of the tangent line with respect to the axis O41 gradually decreases. , It is set so that the shape gradually changes gradually.
Here, according to the first concave curve shape D212, "the slope of the tangent to the axis O41 gradually decreases while the diameter is reduced toward the other side R (of the axis O41)" means that the first concave curve shape D212 It is intended to be a set of tangents of a circle having a center of curvature on the outside of the upper pinch roll R421, and does not necessarily mean that the first concave curve shape D212 includes a portion 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 has a shape in which the diameter is gradually reduced toward the other side R. Further, it is preferable that the inclination of the first edge relief shape E421 with respect to the axis O41 gradually increases from 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 the second profile PR422 is formed on the outer peripheral surface.
The second profile PR422 includes, for example, the second curve shape D22, the second edge relief shape E422 is formed on one side L of the axis O42, and the second curve 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 line with respect to the axis O42 gradually increases while the diameter is gradually reduced.
Here, increasing or decreasing the inclination with respect to the axis O42 is indicated by the absolute value of the inclination with respect to the axis O42.

The second curved shape D22 has a second concave curve shape D221 and a second concave curve shape D221 in which the inclination of the tangent line with respect to the rotating shaft O42 gradually increases while the diameter is increased from one side L of the axis O42 toward the other side R. The second convex curve shape D221 and the second convex curve shape D222 are provided with a second convex curve shape D222 in which the inclination of the tangent line with respect to the axis O42 gradually decreases while being connected to and increasing in diameter toward the other side R. , It is set so that the shape gradually changes gradually.
Here, according to the second concave curve shape D221, "the inclination of the tangent line with respect to the rotation axis O42 gradually increases while the diameter is increased from one side L of the axis O42 toward the other side R" is the second concave curve shape. It is intended that D221 is a set of tangents of a circle having a center of curvature on the outside of 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 the diameter is gradually reduced toward one side. Further, it is preferable that the inclination of the second edge relief shape E422 with respect to the axis O42 gradually decreases from one side L toward the other side R.

In this embodiment, the first curve shape D21 and the second curve shape D22 are curves that can be defined by polynomials of degree 6 (polynomials of degree 3 or higher), respectively, and the first curve shape D21 is on the axis O41. The sixth-order polynomial that defines the second curve shape D22 from the other side R toward the other side R and the sixth-order polynomial that defines the second curve shape D22 from the other side R toward the one side L in the direction of the axis O42 are the same. ..
The polynomial that defines the first curve shape D21 from one side L of the axis O41 toward the other side R and the polynomial that defines the second curve shape D22 from the other side R of the axis O42 toward one side L , Different (not identical) configurations may be used.

Hereinafter, with reference 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). ) Will be explained. FIG. 7B is a diagram showing 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 of one side L of the upper pinch roll R421 is set to 0, the work side end of the other side R is set to 1.0, and the crown at the central position (0.5) in the axial direction is set. Will be described as 0.

In this embodiment, the first curve shape D21 and the second curve shape D22 can be defined by a polynomial of degree 6 (polynomial of degree 3 or higher) as shown in FIG. 7B.
Further, a sixth-order polynomial that defines the first curve shape D21 from one side L of the axis O41 to the other side R, and a sixth-order polynomial that defines the second curve shape D22 from the other side R of the axis O42 to one side L. Are the same.

The crown of the upper pinch roll R421 (first profile PR421) 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.

<Sixth-order polynomial>
R26 (X) = A26 x X ⁶ + B26 x X ⁵ + C26 x X ³ + D26 x X ² + E26 x X + F26
A26 = 19118, B26 = 64084, C26 = 75507, D26 = 4343.6, E26 = 164.19, F26 = 260.884875
Here, R26 (X) indicates the amount of crown (numerical value per radius) from the axis O41, and X indicates the position in the axial direction.

Regarding the 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. An upper pinch is performed so as to geometrically match the profile of the thin-walled slab at the start of casting as shown in (A) and in a state where the shift amount between the upper pinch roll R421 and the lower pinch roll R422 is minimized. The coefficients of each term are determined so that the axial gap distribution between the roll R421 and the lower pinch roll R422 geometrically matches the profile of the thin-walled slab in a steady state as shown in FIG. 11 (C). Is also good.
The above polynomial is an example, and can be arbitrarily set according to conditions and the like.
Further, it goes without saying that by setting the degree of the polynomial to a higher order, it becomes easier to approximate the desired crown.

Next, with reference to FIG. 8, the operation when the casting strip S cast by the twin-drum casting strip continuous casting facility 10 is sent to the in-line mill 50 by the pre-rolling pinch roll device 40 will be described.
FIG. 8 is a schematic view illustrating an operation when the casting strip S is sent to the in-line mill 50 by the pre-rolling pinch roll device 40 according to the second embodiment. The description of the same parts as those in the first embodiment will be omitted.

(1) Before the start of casting, the upper pinch roll R421 and the lower pinch roll R422 are at positions facing each other in the axes O41 and O42 directions (upper pinch roll R421 and lower pinch roll R422 are opposed to each other as shown in FIG. 8A). It is placed at a position that aligns in the width direction).
Then, when starting casting, the upper pinch roll R421 is moved in the direction of the arrow F4211 and the lower pinch roll R422 is moved in the direction of the arrow F4221. For example, the upper pinch roll R421 and the lower pinch roll R422 are formed into a first concave curve shape. D212 and the second concave curve shape D221 are stopped in a state of being 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 equal at any position in the plate width direction (so that the variation is small).
(2) As shown in FIG. 8 (B), for example, in FIG. 8 (A), the first convex curve shape D211 and the second convex curve shape D222 are separated in the axes O41 and O42 directions (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 each other in the directions of the axes O41 and O42) are moved in the directions of the arrows F4212 and F4222.
Then, molten steel (melted metal) is supplied to the molten metal storage portion to form a cast strip.
At this time, the casting strip S421 (S) has a plate profile slightly recessed in the center in the width direction, but the pair of pinch rolls R420 uses the recessed portion of the casting strip S421 (S) as another portion. Pass the plate by sandwiching it 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 solidified shul portion (edge-up portion) is pressed against the solidified shull portion (edge-up portion) by the first edge relief shape E421 and the second edge relief shape E422. Suppression is suppressed.
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 a steady state is reached.
(3) 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 until the casting is started and the casting is reached at the time of steady casting. While passing through the casting strip S12.
From the start of casting to the arrival at 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 casting strip continuous casting facility 10 rises and the center side in the width direction expands. As the diameter (thermal expansion) increases, the concave shape at the center of the casting strip S422 (S) in the width direction gradually becomes smaller (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 narrower 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 becomes equal to or less than the set value) and the first edge relief shape E421 and the second edge relief shape E422 are no longer necessary, the movement in the axis O41 (O42) direction is stopped.
(4) When it reaches the time of steady casting, the movement of the upper pinch roll R421 and the lower pinch roll R422 is stopped as shown in FIG. 8 (D).
When it reaches the time of steady casting, the plate profile of the casting strip S423 (S) does not change, so that 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 the board.

According to the pre-rolling pinch roll device and the pinch roll method according to the second embodiment, the same effect as that of the first embodiment can be obtained.
Further, 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 portion of the casting strip S at the start of casting. Even if there is, it is possible to suppress the reduction (rolling) by pressing the plate width end portion of the casting strip S with a large force.

Hereinafter, examples of the present invention will be described.
Examples were carried out in the manufacturing process of a cast strip having the same configuration as in 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.
Further, the in-line mill is rolled with a rolling reduction of 30%, 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. The pressing force is about 15 tf in total on the left and right.

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

In Comparative Example 2, in the pre-rolling pinch roll apparatus according to the prior art, the roll profile was set to a trapezoidal shape, and the cast strip was provided with an off-center (10 to 120 mm).
Then, the load was controlled so that the pressing force was constant (7.5 tf on the right and 7.5 tf on the left).

In Example 1 of the present invention, the off-center of the cast strip was set to zero by using the pre-rolling pinch roll device provided with the roll profile according to the second embodiment described above.
Then, immediately after the start of casting, the plate end is prevented from contacting the pinch roll, and in the steady state after the start of casting, the shift amount in the pinch roll axis O41 and O42 directions is such that the pinch roll is in contact with the entire plate surface. The load was controlled so that the pressing force was constant (7.5 tf on the right and 7.5 tf on the left).

In Example 2 of the present invention, an off-center (10 to 120 mm) was provided by using a pre-rolling pinch roll device provided with the roll profile according to the second embodiment described above.
Immediately after the start of casting, the end of the plate and the pinch roll are prevented from contacting each other, and in the 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 O41 and O42 directions. The load was controlled so that the pressing force was constant (7.5 tf on the right and 7.5 tf on the left).
Further, by detecting the off-center position of the casting strip, 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 (symmetrical with respect to the center in the width direction of the casting strip). ), And the left and right pinch roll pressing forces were corrected so that the vertical pinch roll axis O41 (O42) direction positions were corrected and the pressing force was made uniform in the plate width direction.

In Comparative Example 1, a stable flying touch could not be achieved until 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 was possible in 5 seconds from the start of casting, and the off gauge was suppressed to about 8 m. However, when the off-center was given by 50 mm or more, the meandering expanded, and finally the cast strip hit the housing post of the pre-rolling pinch roll device and broke.

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.
Further, the meandering was not expanded even if the off-center was given by 50 mm, but the meandering was expanded by giving the off-center by 90 mm or more, and finally the casting strip hit the housing post of the pre-rolling pinch roll device and broke. did.

In Example 2 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.
Moreover, the meandering was not expanded even if the off-center was given by 90 mm.

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

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

For example, in the above embodiment, the case where the pair of pinch rolls R410 and R420 have a profile including a first curve shape and a second curve shape defined by a polynomial of degree 3 or higher has been described. When the profile formed on the surface of the pinch rolls R410 and R420 is defined by a polynomial, the degree of the polynomial may be set arbitrarily.

Further, in the above embodiment, for example, the case where the first curve shapes D11 and D21 and the second convex curve shapes D21 and D22 are defined by a polynomial of degree 3 or higher has been described, but means other than the polynomial (for example, It may be defined by a set of numerical data, etc.). Further, any one of the first convex curve shape, the first concave curve shape, the second concave curve shape, and the second curve shape may be defined by a method other than the polynomial.

Further, in the above embodiment, with respect to the first curve shapes D411 and D421 and the second curve shapes D412 and D422, the first curve shapes D411 and D421 defined from one side and the second curve shapes D412 defined from the other side, The case where D422 is the same has been described, but whether or not the first curve shapes D411 and D421 defined from one side and the second curve shapes D412 and D422 defined from the other side are the same can be arbitrarily set. be able to.

Further, 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, but any of the upper pinch rolls R421 and R421 and the lower pinch rolls R421 and R422 is moved. Can be arbitrarily set, and only one of the upper pinch rolls R421 and R421 and the lower pinch rolls R421 and R422 may be configured to move along the axes O42 and O42.

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

Further, in the above embodiment, the case where the first profile PR421 and the second profile PR422 include the first edge relief shape E421 and the second edge relief shape E422 has been described. For example, the first profile PR421 and the second profile PR421 have been described. 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 either one of the first profile PR421 and the second profile PR422 has the first edge relief shape E421, A configuration may be provided in which the second edge relief shape E422 is provided.

Further, in the above embodiment, a portion whose diameter is increased toward one side L of the first profile PR421 toward the other side R, and a portion whose diameter is increased toward the other side R of the second profile PR422, and toward the other side R of the second profile PR422. Although the case where the diameter is reduced and the case where the diameter is reduced has been described, it can be arbitrarily set whether or not both or one of them is provided, or whether or not the configuration is provided with neither of them.

Further, in the above embodiment, the case where the molten metal is molten steel has been described, but it may be applied to a twin-drum type thin-walled slab continuous casting apparatus using a 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, thin-walled slabs cast by the double-drum type thin-walled slab continuous casting device are passed through an in-line mill while suppressing meandering to reduce the thickness. Since the yield of slabs can be improved, it can be used industrially.

L One side R The other side O1, O2 Axis line (cooling drum)
O42, O42 axis (rotation axis (pinch roll))
S casting strip (thin wall slab)
T Tandish 10 Twin-drum type casting strip continuous casting equipment (Twin-drum type thin-walled slab continuous casting equipment)
R10 Pair of cooling drums R11 1st cooling drum R12 2nd cooling drum 11 Dummy sheet 12 Projection part 13 Dummy bar 15 Metal molten metal storage part 20 Antioxidant device 30 Cooling device 40 Pre-rolling pinch roll device 40A, 40B Position detection devices R421, R421 Upper pinch roll (1st pinch roll)
R421, R422 lower pinch roll (second pinch roll)
PR11, PR21 1st profile PR12, PR22 2nd profile D11, D21 1st curve shape D12, D22 2nd curve shape D111, D211 1st convex curve shape D112, D212 1st concave curve shape E421 1st edge relief shape D121, D221 2nd convex curve shape D122, D222 2nd concave curve shape E422 2nd edge relief shape 42 Housing 42A, 42B Roll chock 43A Top rolling load detection device 43B Bottom rolling load detection device 44 Electric reduction device (reduction means)
50 In-line mill 51A, 51B Work roll 52A, 52B Intermediate roll 53A, 53B Backup roll 54 In-line mill control device 542 Hydraulic reduction cylinder 542 Mill hydraulic reduction device 543 Roll rotation speed setting means 544 Roll bending force setting means 545 Roll cross angle setting means 55 Plate thickness meter 60 Pinch roll device after rolling 81 Feed roll 82, 83 Tension roll 84 Deflector roll 70 Winding device

Claims (9)

A twin drum type in which a metal molten metal storage portion is formed by a pair of cooling drums and a side dam, and the metal molten metal stored in the metal molten metal storage portion is solidified, grown and cast on the peripheral surface while rotating the pair of cooling drums. Thin-walled slab A pre-rolling pinch-roll device that feeds thin-walled slabs formed in a continuous casting device to an in-line mill by a pair of pinch rolls.
The pair of pinch rolls
A first convex curved shape absolute value of the tangent of the inclination becomes gradually larger from one side of the rotational axis relative to the rotational axis while being reduced in diameter toward the other side, connected to the other side of the first convex curve shape A first profile including a first curved shape having a first concave curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually decreases while being reduced in diameter toward the other side is formed on the outer peripheral surface. With the first pinch roll
It is connected to a second concave curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually increases while the diameter is increased from one side of the rotation axis toward the other side, and the other side of the second concave curve shape. A second profile including a second convex curve shape having a second convex curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually decreases while the diameter is increased toward the other side is formed on the outer peripheral surface. With the second pinch roll,
With
A pre-rolling pinch roll device characterized in that the first pinch roll and the second pinch roll are configured to be relatively movable along the rotation axis. The pre-rolling pinch roll device according to claim 1.
A pre-rolling pinch roll apparatus, wherein at least one of the first curved shape and the second curved shape is defined by a polynomial. The pre-rolling pinch roll apparatus according to claim 1 or 2.
A first edge relief shape connected to the other side of the first curved shape and reduced in diameter toward the other side, and a first edge relief shape connected to the one side of the second curved shape toward the other side. Therefore, a pre-rolling pinch roll device comprising at least one of the reduced diameter second edge relief shapes. A twin drum type in which a metal molten metal storage portion is formed by a pair of cooling drums and a side dam, and the metal molten metal stored in the metal molten metal storage portion is solidified, grown and cast on the peripheral surface while rotating the pair of cooling drums. Thin-walled slab A pre-rolling pinch-roll method in which thin-walled slabs formed in a continuous casting apparatus are sent to an in-line mill by a pair of pinch rolls.
The pair of pinch rolls
A first convex curved shape absolute value of the tangent of the inclination becomes gradually larger from one side of the rotational axis relative to the rotational axis while being reduced in diameter toward the other side, connected to the other side of the first convex curve shape A first profile including a first curved shape having a first concave curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually decreases while being reduced in diameter toward the other side is formed on the outer peripheral surface. With the first pinch roll
It is connected to a second concave curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually increases while the diameter is increased from one side of the rotation axis toward the other side, and the other side of the second concave curve shape. A second profile including a second convex curve shape having a second convex curve shape in which the absolute value of the inclination of the tangent to the rotation axis gradually decreases while the diameter is increased toward the other side is formed on the outer peripheral surface. With the second pinch roll,
With
A pre-rolling pinch roll method, characterized in that the first pinch roll and the second pinch roll are configured to be relatively movable along the rotation axis. The pre-rolling pinch roll method according to claim 4 .
A pre-rolling pinch-roll method, characterized in that at least one of the first curved shape and the second curved shape is defined by a polynomial. The pre-rolling pinch roll method according to claim 4 or 5 .
A first edge relief shape connected to the other side of the first curved shape and reduced in diameter toward the other side, and a first edge relief shape connected to the one side of the second curved shape toward the other side. Therefore, the pre-rolling pinch roll method comprising at least one of the reduced diameter second edge relief shapes. The pre-rolling pinch roll method according to any one of claims 4 to 6 .
Based on a plate profile of previously obtained castings after the start due to the elapsed time the thin cast strip, and controlling the relative movement of the rotation axis direction of the first pinch roll and said second pinch roll rolling Front pinch roll method. The pre-rolling pinch roll method according to any one of claims 4 to 7 .
A position detecting device for detecting the position in the width direction of the thin-walled slab is provided at least one of the front of the pair of pinch rolls in the plate-passing direction and the rear of the plate-passing direction.
Based on the position in the width direction of the thin-walled slab detected by the position detection device, the pair of pinch rolls sandwich the thin-walled slab symmetrically with respect to the center in the width direction of the thin-walled slab. A pre-rolling pinch roll method characterized by controlling the relative movement amount of. The pre-rolling pinch roll method according to claim 8 .
A pre-rolling pinch roll method characterized in that the pressing force of the pair of pinch rolls is controlled so that the moments generated on the left and right sides are equal to the center of the thin-walled slab in the width direction.

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