JP6787028B2 - Double-drum type thin-walled slab continuous casting equipment and thin-walled slab manufacturing method - Google Patents

Description

The present invention relates to a double-drum type thin-walled slab continuous casting apparatus provided with a pair of cooling drums for continuous casting, and a method for producing thin-walled slabs.

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 strips delivered from the cooling drum are horizontally fed by pinch rolls and adjusted to the 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 reduction device can control the hydraulic 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 passes 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, and the casting strip is pulled out to start casting. ing.
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 double-drum thin-walled casting strip continuous casting facility, the cooling drum is generally cold before the start of casting. When 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. The period after the temperature of the cooling drum reaches a certain level is called steady casting, the temperature of the cooling drum during steady casting is called steady temperature, and such a state is called steady state.

The profile of the cooling drum changes with the elapsed time from the start of casting to the arrival at the time of 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 case where the cooling drum is cast without shifting and the in-line mill is not reduced.

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 in the case of FIG. It is almost the same as, and it takes about 30 seconds from the start of casting.

From the above, the casting strip S301 from the start of casting to the time of steady casting has 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, which is shown in FIG. As shown in the case of S301 in FIG. 11 (A) immediately after the start of casting, as in S302 in FIG. 11 (B) after a while after the start of casting, and in the steady state as in S303 in FIG. 11 (C). It becomes the plate profile of the casting strip.

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 on the in-line mill inlet side is about 1000 ° C., so that the metal flow (width spread) in the plate width direction occurs. Although a small amount of plate crown adjustment is possible, the in-line mill has sufficient crown control capability to accommodate cast strips of plate profile as shown in FIGS. 11 (A) and 11 (B). Not.

On the other hand, when the cast strip of the plate profile as shown in FIG. 11 is rolled with a large force to adjust the crown amount by an in-line mill, the thick plate width center portion and plate width end portion are extended more in the longitudinal direction. As a result, the center elongation at the center of the plate width and the edge elongation at the end of the plate width become extremely large, so that the cast strip is easily broken.

Further, the flying touch is started in the in-line mill, 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.
In addition, edge-up and convex crown may cause instability during winding and C warp (warp in the plate width direction) when the wound cast strip is rewound in the next process, resulting in edge-up and convex crown. Measures to reduce the convex crown have also been requested.

The off-gauge of such a casting strip is caused by rolling the casting strip as shown in FIGS. 11A and 11B, and the casting strip capable of starting the flying touch at an early timing is cast. It is necessary.

Therefore, in order to reduce the influence of thermal expansion from the start of casting of the concave profile in the cooling drum to the steady state, for example, the cooling drum is heated from the outside with a heater in advance, and the temperature distribution of the cooling drum at the start of casting. It is conceivable to reduce the bias of.

Japanese Unexamined Patent Publication No. 2000-343103

However, when a dummy sheet is connected and casting is started in a double-drum type thin-walled casting strip continuous casting facility, the cooling drum is not rotating when the dummy sheet is connected, and the cooling drum is uniformly heated over the entire circumference. It's difficult to do. Furthermore, since the heat that escapes from the contact portion of the cooling drum with the dummy sheet becomes large, the amount of thermal expansion differs in the circumferential direction of the cooling drum, and the plate profile of the casting strip corresponds to the circumferential length pitch of the cooling drum. It raises new and fluctuating problems.

Therefore, there is a demand for a technique capable of shortening the time until the flying touch when manufacturing a thin-walled slab while rotating a pair of cooling drums by a twin-drum type thin-walled slab continuous casting apparatus.

The present invention has been made in view of such a problem, and a pair of cooling drums by injecting molten metal into a pair of rotatable cooling drums and a molten metal storage portion formed by a side dam. When a thin-walled slab is manufactured by solidifying and growing molten metal on the peripheral surface of a cooling drum while rotating the metal, by shortening the time until flying touch, off-gauge is suppressed and the yield is reduced. It is an object of the present invention to provide a twin-drum type thin-walled slab continuous casting apparatus and a method for manufacturing thin-walled slabs, which can be improved and thus can reduce the manufacturing cost of thin-walled slabs.

Therefore, the inventors of the present invention store the molten metal in a pair of rotatable cooling drums and a molten metal storage portion formed by a side dam, and rotate the pair of cooling drums to rotate the molten metal. As a result of diligent research on a technique for shortening the time from the start of casting until the off-gauge does not occur in the thin-walled slab when the thin-walled slab is manufactured by solidifying and growing on the peripheral surface of the cooling drum. It was found that it is effective to bring the plate profile of the thin-walled slab sent to the in-line mill evenly close to each other, and the means shown below are effective.
(1) When a pair of cooling drums are moved relative to each other along the axis, a deep concave part (center part in the width direction) and a shallow concave part (close to the end in the width direction) of the cooling drum are combined. Even if the influence of the concave shapes is canceled out and the depth of the concave shapes changes depending on the temperature of the cooling drum, a thin-walled slab having a plate profile with a small crown amount at the center of the plate width can be efficiently produced. be able to.
(2) When manufacturing by moving the pair of cooling drums relative to each other along the axis, the distance between the pair of cooling drums is reduced at the portion forming the plate width end of the thin-walled slab at the start of casting. Even if the solidified shell becomes thicker, the amount of edge-up can be efficiently reduced.

In order to solve the above problems, the present invention proposes the following means.
According to the first aspect of the present invention, the molten metal is injected into a pair of cooling drums which are rotatable around an axis arranged parallel to each other and a molten metal storage portion formed by a side dam, and the pair of cooling is performed. Double-drum type thin-walled casting that manufactures thin-walled slabs by rotating the peripheral surfaces of the drums facing each other downward to solidify and grow the molten metal injected into the molten metal storage section on the peripheral surfaces of the pair of cooling drums. In a single continuous casting device, the pair of cooling drums has a first convex curve shape in which the absolute value of the inclination of the tangent to the axis gradually increases while the diameter is reduced from one side to the other of the axis. A first curved shape including a first concave curve shape which is connected to the first convex curve shape and whose diameter is reduced toward the other side while the absolute value of the inclination of the tangent to the axis gradually decreases. A first cooling drum in which one profile is formed on the outer peripheral surface, and a second concave curve shape in which the absolute value of the slope of the tangent to the axis gradually increases while the diameter increases from one side of the axis toward the other. A second curve shape including a second convex curve shape which is connected to the second concave curve shape and whose diameter is increased toward the other side while the absolute value of the inclination of the tangent to the axis gradually decreases. A second cooling drum having two profiles formed on the outer peripheral surface thereof is provided, and the first cooling drum and the second cooling drum are configured to be relatively movable along the axis, and have the shape of the first curve. A first edge suppression shape connected to the one side and increased in diameter toward the one side, and a second shape connected to the other side of the second curved shape and increased in diameter toward the other side. It is characterized by having at least one of two edge suppression shapes .

The invention according to claim 4 is a method for producing a thin-walled slab, the first convex in which the absolute value of the inclination of the tangent to the axis gradually increases while the diameter is reduced from one side of the axis toward the other. A first curved shape having a curved shape and a first concave curved shape that is connected to the first convex curved shape and whose diameter is reduced toward the other side while the absolute value of the slope of the tangent to the axis gradually decreases. The first cooling drum in which the first profile containing the above is formed on the outer peripheral surface, and the second concave curve in which the absolute value of the slope of the tangent to the axis gradually increases while the diameter is increased from one side of the axis toward the other. A second curved shape having a shape and a second convex curved shape that is connected to the second concave curved shape and whose diameter is increased toward the other side while the absolute value of the inclination of the tangent to the axis gradually decreases. first edge suppressing shape which is enlarged in accordance with the second profile is e Bei second cooling drum formed on the outer circumferential surface, and toward the one side the one is connected to the side of the first curved shape including A pair of cooling drums having at least one of the second edge suppression shapes connected to the other side of the second curved shape and increasing in diameter toward the other side, and the pair of cooling drums. The metal molten metal is injected into the metal molten metal storage portion formed by the side dams arranged on both sides in the width direction, and the pair of cooling drums are injected into the metal molten metal storage portion by rotating the peripheral surfaces facing each other downward. It is characterized in that the molten metal is solidified and grown on the peripheral surfaces of the pair of cooling drums, and thin-walled slabs are cast while the first cooling drum and the second cooling drum are relatively moved along the axis. To do.

According to the twin-drum type thin-walled slab continuous casting apparatus and the method for manufacturing thin-walled slabs according to the present invention, the outer peripheral surface is a first profile including a first curved shape having a first convex curve shape and a first concave curve shape. A pair including a first cooling drum formed in the above surface and a second cooling drum having a second profile formed on the outer peripheral surface including a second curved shape having a second concave curve shape and a second convex curve shape. While moving the first cooling drum and the second cooling drum relative to each other along the axis, the molten metal stored in the molten metal storage section is solidified and grown to cast a thin-walled slab. The unevenness formed on the thin-walled slab after the start can be reduced, and the time until the flying touch can be shortened.
Further, since the pair of cooling drums has at least one of the first edge suppressing shape and the second edge suppressing shape, a thick solidified shell is formed at the plate width end portion of the thin sheet slab at the start of casting. However, it is possible to suppress the occurrence of edge-up.
As a result, the occurrence of off-gauge in the production of thin-walled slabs can be reduced and the yield can be improved.

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, it is assumed that the first profile and the second profile may include a shape portion other than the first curve shape and the second curve shape.
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 double-drum type thin-walled slab continuous casting 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 being done.

The invention according to claim 5 is the method for producing a thin-walled slab according to claim 4 , wherein at least one of the first curved shape and the second curved shape is a pair defined by a polynomial. It is characterized by using the cooling drum of.

According to the twin-drum type thin-walled slab continuous casting apparatus and the method for manufacturing thin-walled slabs according to the present invention, at least one of the first curved shape and the second curved shape is a pair of cooling drums defined by a polypoly. Therefore, the first curve shape and the second curve shape can be defined efficiently and surely, and a pair of cooling drums can be efficiently manufactured.
As a result, the manufacturing cost of the pair of cooling drums can be reduced.

In this specification, at least one of the first curve shape and the second curve shape is defined by a polynomial, except when both the first curve shape and the second curve shape are defined by a polynomial. It is assumed that only one of the curved shape and the second curved shape is defined by the polynomial. If the plate profiles on one surface and the other surface of the thin-walled slab are not symmetrical in the plate width direction (from one side to the other side in the axial direction and from the other side to one side), the first curved shape and the first curve shape are obtained. 2 It may be effective to make the curved shape asymmetric in the plate width direction. On the other hand, when it is symmetrical in the plate width direction, it is preferable that the first curve shape and the second curve shape are symmetrical in the plate width direction.

The invention according to claim 3 is the twin-drum type thin-walled slab continuous casting apparatus according to claim 1, wherein at least one of the first curved shape and the second curved shape is of a third order or higher. It is characterized by being defined by a polynomial.

The invention according to claim 6 is the method for producing a thin-walled slab according to claim 4 , wherein at least one of the first curved shape and the second curved shape is defined by a polynomial of degree 3 or higher. It is characterized by using a pair of cooling drums.

According to the double-drum type thin-walled slab continuous casting apparatus and the method for producing thin-walled slabs according to the present invention, at least one of the first curved shape and the second curved shape is defined by a polymorphism of degree 3 or higher. Since the pair of cooling drums is used, the first curved shape and the second curved shape can be easily and efficiently defined, and the pair of cooling drums can be efficiently manufactured.

In this specification, the fact that at least one of the first curve shape and the second curve shape is defined by a polynomial of degree 3 means that both the first curve shape and the second curve shape are defined by a polynomial of degree 3 or higher. In addition to the case where only one of the first curve shape and the second curve shape is defined by a cubic polynomial, it is assumed.

In this specification, a pair of cooling drums having at least one of a first edge suppressing shape and a second edge suppressing shape means that the pair of cooling drums has both a first edge suppressing shape and a second edge suppressing shape. In addition to the case where the cooling drums are provided, the case where the pair of cooling drums is provided with only one of the first edge suppressing shape and the second edge suppressing shape is included.

The invention of claim 7 is a method for producing a thin cast strip according to claims 4 to any one of claims 6, a change of the cooling drum with the elapsed time after the start of pre-acquired cast It is characterized in that the relative movement amount of the first cooling drum and the second cooling drum in the axial direction is controlled based on the plate profile of the thin-walled slab.

According to the twin-drum type thin-walled slab continuous casting apparatus and the thin-walled slab manufacturing method according to the present invention, based on the change in the cooling drum with the elapsed time after the start of casting and the plate profile of the thin-walled slab obtained in advance. Since the relative movement amount of the first cooling drum and the second cooling drum in the axial direction is controlled, it is possible to efficiently manufacture a thin-walled slab with less unevenness of unevenness.

In this specification, the change in the cooling drum with the elapsed time after the start of casting and the acquisition of the plate profile of the thin-walled slab in advance include not only the case of acquiring by experiment but also the case of acquiring by a method other than experiment such as simulation. It shall be a waste.
Further, when controlling the relative movement amount of the first cooling drum and the second cooling drum in the axial direction, when moving at a constant speed, when moving while changing the moving speed according to parameters such as the elapsed time after casting. It shall include.

According to the twin-drum type thin-walled slab continuous casting apparatus and the thin-walled slab manufacturing method according to the present invention, it is possible to shorten the time from the start of casting to the flying touch and improve the yield of the thin-walled slab. it can. As a result, the manufacturing cost of the thin-walled slab 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 schematic block diagram explaining an example of the twin drum type casting strip continuous casting equipment which concerns on 1st Embodiment of this invention. It is a figure explaining an example of the schematic structure of the pair of cooling drums 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 which concerns on 1st Embodiment of this invention. It is a figure explaining the schematic structure 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 a schematic diagram explaining the operation 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 a figure explaining an example of the schematic structure of the cooling drum which concerns on 2nd Embodiment of this invention. It is the schematic explaining the operation at the time of manufacturing a cast strip by applying the cooling drum 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). 3A and 3B are diagrams for explaining the schematic configuration of the 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 process 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 first pinch. It includes a roll 40, an in-line mill 50, a second pinch roll 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 first pinch roll 40, the in-line mill 50, the second pinch roll 60, and winding are performed. The devices 70 are arranged in this order.

Further, a feed roll 81 is arranged between the twin drum type casting strip continuous casting facility 10 and the first pinch roll 30.
Further, a tension roll 82 is arranged between the first pinch roll 40 and the in-line mill 50, and a tension roll 83 is arranged between the in-line mill 50 and the second pinch roll 60.
Further, a deflector roll 84 is arranged between the second pinch roll 60 and the winding device 70.

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 dams (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 dams form a molten metal storage unit 15.

The pair of cooling drums R10 includes a first cooling drum R11 and a second cooling drum R12, and corresponds to the plate thickness (internal quality) of the cast strip S to be manufactured, the first cooling drum R11 and the second cooling drum R12. It is possible to adjust the interval (distance between the axes of rotation).

Further, as shown in FIG. 3A, the first cooling drum R11 and the second cooling drum R12 are controlled to move in the directions of arrows F11 and F12 along the drum width directions (axis lines O1 and O2).
The amount of movement of the first cooling drum R11 and the second cooling drum R12 is the plate of the casting strip S and the thermal expansion due to the temperature change of the first cooling drum R11 and the second cooling drum R12 with the elapsed time after the start of casting acquired in advance. It is set based on the profile.

Further, the amount of movement of the first cooling drum R11 and the second cooling drum R12 is set based on, for example, the change of the pair of cooling drums R10 with the elapsed time after the start of casting and the plate profile of the casting strip S acquired by the experiment. ing. It should be noted that the setting may be made based on a simulation regardless of the experiment, or may be configured to be controlled in real time based on the data acquired by the plate profile type.

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. ..

As shown in FIG. 3A, the first cooling drum R11 is configured to be rotatable around the axis O1, and the first profile PR11 is formed on the outer peripheral surface.
The first profile PR11 includes, for example, the first curved shape C11, and the first curved shape C11 is once expanded in diameter from one side L of the axis O1 toward the other side R and then reduced in diameter. It has a convex curve shape C111 and a first concave curve shape C112 connected to the first convex curve shape C111 and once reduced in diameter toward the other side R and then expanded in diameter. The diameter reduction and diameter expansion of the first curved shape C11 are set so as to gradually and gradually change the shape.

The first curve shape C11 will be described in more detail. The first convex curve shape C111 and the first convex curve shape C111 in which the slope of the tangent line with respect to the axis O1 gradually increases while the diameter is reduced from one side L of the axis O1 toward the other side R. It has a first concave curve shape C112 that is connected to the one convex curve shape C111 and whose diameter is reduced toward the other side R while the slope of the tangent to the axis O1 gradually decreases.
Here, increasing or decreasing the inclination with respect to the axis O1 is indicated by the absolute value of the inclination with respect to the axis O1.

As shown in FIG. 3A, the second cooling drum R12 is configured to be rotatable around the axis O2, and the second profile PR12 is formed on the outer peripheral surface.
The second profile PR12 includes, for example, the second curved shape C12, and the second curved shape C12 is once reduced in diameter from one side L of the axis O2 toward the other side R and then expanded in diameter. It has a concave curve shape C121 and a second convex curve shape C122 which is connected to the second concave curve shape C121 and is once expanded in diameter toward the other side R and then reduced in diameter. The diameter reduction and diameter expansion of the second curved shape C12 are set so as to gradually and gradually change the shape.

Explaining the second curve shape C12 in more detail, the second concave curve shape C121 and the second concave curve shape C121 in which the slope of the tangent line with respect to the axis O2 gradually increases while the diameter is increased from one side L of the axis O2 toward the other side R. It has a second convex curve shape C122 which is connected to the two concave curve shape C121 and whose diameter is increased toward the other side R while the inclination of the tangent to the axis O2 is gradually reduced.
Here, increasing or decreasing the inclination with respect to the axis O2 is indicated by the absolute value of the inclination with respect to the axis O2.

In this embodiment, the first curve shape C11 and the second curve shape C12 are curves that can be defined by a cubic polynomial, respectively, and the first curve shape C11 is changed from one side L to the other side R of the axis O1. The cubic polynomial that defines the second curve shape C12 from the other side R to the one side L in the axis O2 direction is the same.
The polynomial that defines the first curve shape C11 from one side L of the axis O1 to the other side R and the polynomial that defines the second curve shape C12 from the other side R in the axis O2 direction to the other side L are different ( It may be configured (not the same).

Hereinafter, with reference to FIG. 3B, taking the first profile PR11 of the first cooling drum R11 according to the first embodiment as an example, the crowns of the first cooling drum R11 and the second cooling drum R12 (first profile PR11, first profile PR11, first 2 Profile PR12) will be described. FIG. 3B is a diagram showing an example of a third-order polynomial (or fourth-order polynomial) related to the first profile PR11 of the first cooling drum R11.
As shown in FIG. 3B, the drive side end of one side L of the first cooling drum R11 is set to 0, the work side end of the other side R is set to 1.0, and the center position (0.5) in the axial direction is set. The crown will be described as 0.

In this embodiment, the first curve shape C11 (second curve shape C12) 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. 3B.
Further, for example, a third-order or higher term expression that defines the first curve shape C11 from one side L of the axis O1 toward the other side R and the second curve shape C12 from the other side R of the axis O2 to one side L. The polynomials of degree 3 or higher defined toward each other are the same.

The crown of the first cooling drum R11 (first profile PR11) is as shown in FIG. 3B.
FIG. 3B shows an example of a third-order polynomial and a fourth-order polynomial constituting the crown of the first cooling drum R11.
Regarding the specific method of obtaining the polynomial, for example, when the gap between the first cooling roll R11 and the second cooling roll R12 is the desired thickness of the thin-walled slab, the roll axis is before the movement in the roll axis direction. When the roll gap distribution in the direction geometrically matches the profile of the desired thin-walled slab and is moved in the roll axis direction, the maximum amount of expansion of the roll gap is the first cooling roll R11 or The coefficients of each term may be determined so as to be equal to or greater than the amount of thermal expansion in the radial direction of the second cooling roll R12 in the steady state. The amount of thermal expansion in the radial direction of the first cooling roll R11 or the second cooling roll R12 may be obtained by heat conduction calculation, or the roll gap distribution in the roll axis direction before the start of casting and in the steady state is measured. You may ask for it.

<3rd order polynomial>
The crown of the first cooling drum R11 can be represented by, for example, the following third-order polynomial.
R13 (X) = A13 x X ³ + B13 x X ² + C13 x X + D13
A13 = 6539.8, B13 = 7899.8, C13 = 1715.6,
D13 = 33.427
Here, R13 (X) indicates the amount of crown (numerical value per radius) from the axis O1, and X indicates the position in the axial direction.

<4th order polynomial>
The crown of the first cooling drum R11 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 = 6002.3, B14 = 5644.9, C14 = 396.85,
D14 = 250.97, E14 = 9.7902
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.

In this embodiment, the first cooling drum R11 and the second cooling drum R12 shown in FIGS. 3A and 3B have, for example, an outer diameter of 800 mm and a drum body length (width) of 1500 mm. 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. 4, the first pinch roll 40 has, for example, position detection devices 40A and 40B, upper pinch roll R40A, lower pinch roll R40B, housing 41, roll chock 42A and 42B, and upper rolling load detection. A device 43A, a lower rolling load detecting device 43B, and an electric reduction device (reduction means) 44 are provided. Further, for example, a hydraulic reduction cylinder is installed in a housing located above the backup roll chock above the casting strip.

The upper and lower pinch rolls R40A and R40B 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 R40A and R40B have, for example, a roll diameter of 400 mm and a roll body length (width) of 2000 mm.

Further, the upper and lower pinch rolls R40A and R40B 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 R40A is connected to the reduction device (reduction means) 44 via the upper rolling load detection device 43A, and the lower pinch roll R40B is connected to the lower rolling load detection device 43B.

Then, when the electric reduction device 44 reduces the upper pinch roll R40A, the reduction load of the upper and lower pinch rolls R40A and R40B is detected, and the casting strip S is tensioned between the first pinch roll 40 and the in-line mill 50. It has become.

The tension generated between the first pinch roll 40 and the in-line mill 50 is measured by a tension roll 82 provided between the first pinch roll 40 and the in-line mill 50, and is measured between the first pinch roll 40 and the in-line mill 50. The speed of the first pinch roll is controlled so that the generated tension becomes a preset tension.

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 that are opposed to 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 the 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 second pinch roll 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 system) (not shown), and the pinch roll is provided by the reduction device. Is reduced to generate tension in the casting strip S with and from the in-line mill 50.

The tension between the in-line mill 50 and the second pinch roll 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 second pinch roll 60 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 rolled by the in-line mill 50 and sent out from the second pinch roll 60 via the deflector roll 84 and winds it into a coil.

Hereinafter, the production of the cast strip by 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 the 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 unit 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 casting strip S is sent to the in-line mill 50 by the first pinch roll 40 while generating tension between the first pinch roll 40 and the in-line mill 50.
(8) The in-line mill 50 starts the flying touch at a preset timing in which the plate profile of the casting strip S is expected to have a predetermined shape after the protrusion 12 has passed through the in-line mill 50.
(9) The in-line mill 50 rolls the casting strip S to adjust the plate thickness to a desired value.
(10) Next, the second pinch roll 60 sends the casting strip S from the in-line mill 50 to the winding device 70 while generating tension between the in-line mill 50 and the second pinch roll 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 is manufactured by the twin drum type casting strip continuous casting facility 1 will be described.
FIG. 6 is a schematic view illustrating the operation when the casting strip S is manufactured by the twin drum type casting strip continuous casting facility 1. In FIG. 6, the effects of edge-up and thermal expansion are omitted.

(1) Before the start of casting, as shown in FIG. 6A, the first cooling drum R11 and the second cooling drum R12 are at positions facing each other in the axes O1 and O2 directions (for example, the first cooling drum R11). The second cooling drum R12 is arranged at a position where it is aligned in the width direction).
When starting casting, the first cooling drum R11 is moved in the direction of arrow F111, and the second cooling drum R12 is moved in the direction of arrow F121. As a result, the roll gap between the cooling drum R11 and the second cooling drum R12 changes.
(2) As shown in FIG. 6B, for example, the first cooling drum R11 and the second cooling drum R12 are close to each other in the axes O1 and O2 directions by the first convex curve shape C111 and the second convex curve shape C122. Stop at the position.
Then, the molten steel (melted metal) is supplied to the molten metal storage portion composed of the first cooling drum R11 and the second cooling drum R12.
Since the first convex curve shape C111 and the second convex curve shape C122 are close to each other in the supplied molten steel, the plate thickness at the center in the plate width direction is thin and the plate thickness at the end in the plate width direction is thick. A profile, that is, a cast strip S11 having a concave plate profile in the plate width direction recessed in the plate thickness direction is formed.
After the casting is started, the first cooling drum R11 is moved in the direction of the arrow F112, and the second cooling drum R12 is moved in the direction of the arrow F122.
(3) As shown in FIG. 6C, the first cooling drum R11 is moved in the direction of arrow F113 and the second cooling drum R12 is moved in the direction of arrow F123 from the start of casting to the time of steady casting. The casting strip S12 is cast while moving. As a result, the cast strip S11 changes in the plate profile direction in which the plate thickness at the central portion in the plate width direction is thick and the plate thickness at the end portion in the plate width direction is thin as the amount of movement changes, that is, it is slightly concave in the plate width direction. A cast strip S12 having a plate profile of is formed.
The first cooling drum R11 and the second cooling drum R12 move in the directions of arrow F113 and arrow F123, respectively, until the set timing at which the in-line mill 50 starts the flying touch.
(4) When it reaches the time of steady casting, the movement of the first cooling drum R11 and the second cooling drum R12 is stopped as shown in FIG. 6D.
As a result, at the time of steady casting, the first cooling drum R11 and the second cooling drum R12 reach steady state, the first profile and the second profile do not change, and the plate profile of the casting strip S13 becomes substantially uniform.
Further, in a steady state, when the cooling drum R10 is moved as shown in FIG. 6D, a concave (asymmetric in the axial direction) crown is attached to the cooling drum R10 to make the cast strip a desired plate crown, thereby causing thermal expansion. The impact is mitigated.
Due to this crown, changes as shown in FIG. 10 occur in the cooling drum from immediately after casting to the steady state, but as shown in FIG. 6 (B) immediately after the start of casting and as shown in FIG. 6 (D) in the steady state. , The change in the cooling drum is offset by moving the cooling drum R10.
Regarding the amount of movement of the above drum, the profile of the cooling drum gap is obtained so that the desired plate profile can be obtained from the relationship between the change in the cooling drum with the elapsed time after the start of casting and the plate profile of the thin-walled slab obtained in advance. The amount of movement in the roll axis direction that serves as the profile may be obtained geometrically. The change in the cooling drum may be obtained in advance by heat transfer calculation, or may be obtained by experiment in advance. The plate profile of the thin-walled slab may be mathematically expressed in advance by experimenting with the change in the plate profile of the thin-walled cast strip after the start of casting in correspondence with the time after the start of casting.
For example, the amount of movement of the first cooling drum R11 and the second cooling drum R12 may be calculated so that the roll gap distribution in the roll axis direction geometrically cancels the amount of thermal expansion of the roll during casting.

According to the twin drum type casting strip continuous casting apparatus 1 and the method for manufacturing the casting strip S according to the first embodiment, the unevenness formed on the casting strip S after the start of casting due to the influence of the thermal expansion of the cooling drum is determined. It can be made smaller to shorten the time to fly touch.
As a result, the occurrence of off-gauge in the production of the cast strip S can be reduced and the yield can be improved.

According to the method for manufacturing the twin drum type casting strip continuous casting apparatus 1 and the casting strip S according to the first embodiment, the first curve shape C11 and the second curve shape C12 are defined by a polymorphism of degree 3 or higher. , The first curved shape C11 and the second curved shape C12 can be easily and efficiently defined, and a pair of cooling drums R10 can be efficiently manufactured.
As a result, the manufacturing cost of the pair of cooling drums R10 can be reduced.

According to the method for manufacturing the twin-drum type casting strip continuous casting apparatus 1 and the casting strip S according to the first embodiment, the temperature changes of the first cooling drum R11 and the second cooling drum R12 with the elapsed time after the start of casting acquired in advance. And the plate profile of the casting strip S are used to control the amount of movement of the first cooling drum R11 and the second cooling drum R12 in the axes O1 and O2 directions, so that the casting strip S with less unevenness is efficiently manufactured. can do.

<Second Embodiment>
Next, a second embodiment of the present invention will be described with reference to FIGS. 1, 2, 4, 5, 5, 7, and 8. Note that FIGS. 1, 2, 4, and 5 are the same as those in the first embodiment, and thus description thereof will be omitted. FIG. 7 is a diagram illustrating a schematic configuration of a cooling drum according to the second embodiment. In FIGS. 1, 2, and 7, reference numeral R20 indicates a pair of cooling drums.

The second embodiment is an example that is effective for both the influence of thermal expansion and the edge-up of the cast strip. In the first embodiment, it is possible to reduce the unevenness of the unevenness formed on the casting strip S after the start of casting due to the influence of thermal expansion of the cooling drum, but the edge due to solidification and cooling of the casting strip. The purpose is to get a big effect on the up.

The pair of cooling drums R20 includes a first cooling drum R21 and a second cooling drum R22, and the distance between the first cooling drum R21 and the second cooling drum R22 (of the rotating shaft) corresponds to the thickness of the casting strip S. The distance between the axes) can be adjusted.
Further, as shown in FIG. 7, the first cooling drum R21 and the second cooling drum R22 can be controlled to move relative to the arrows F21 and F22 along the drum width directions (axis lines O1 and O2). ing.

As shown in FIG. 7, the first cooling drum R21 has a first profile PR21 formed on the outer peripheral surface of the axis O1.
The first profile PR21 includes, for example, a first curved shape C21 and a first edge suppressing shape E21.

The first curved shape C21 is connected to the first convex curve shape C211 and the other side connected to the first convex curve shape C211 and the diameter is increased and then reduced from one side L of the axis O1 toward the other side R. It has a first concave curved shape C212 whose diameter is once reduced toward R and then expanded. The diameter reduction and diameter expansion of the first curved shape C21 are set so as to gradually and gradually change the shape.

The first curve shape C21 will be described in more detail. The first convex curve shape C211 and the first convex curve shape C211 in which the slope of the tangent line with respect to the axis O1 gradually increases while the diameter is reduced from one side L of the axis O1 toward the other side R. It has a first concave curve shape C212 which is connected to the one convex curve shape C211 and whose diameter is reduced toward the other side R while the inclination of the tangent line with respect to the axis O1 gradually decreases.
Here, increasing or decreasing the inclination with respect to the axis O1 is indicated by the absolute value of the inclination with respect to the axis O1.

The first edge suppression shape E21 is connected to the tangent line of the first convex curve shape C211 in the vicinity of the maximum value of the polynomial in the one side L of the first convex curve shape C211, and goes from the other side R toward the one side L. Therefore, the shape is gradually expanded. That is, the shape is gradually reduced in diameter from one side L to the other side R.
Further, the first edge suppression shape E21 is formed so that, for example, the inclination with respect to the axis O1 gradually decreases from one side L toward the other side R.

As shown in FIG. 7, the second cooling drum R22 has a second profile PR22 formed on the outer peripheral surface thereof.
The second profile PR22 includes, for example, a second curved shape C22 and a second edge suppressing shape E22.

The second curved shape C22 is connected to the second concave curved shape C221 and the other side connected to the second concave curved shape C221, which is once reduced in diameter and then expanded in diameter from one side L of the axis O2 toward the other side R. It has a second convex curve shape C222 whose diameter is increased and then reduced toward R. The diameter reduction and diameter expansion of the second curved shape C22 are set so as to gradually and gradually change the shape.

Explaining the second curve shape C21 in more detail, the second concave curve shape C221 and the second concave curve shape C221 in which the slope of the tangent line with respect to the axis O2 gradually increases while the diameter is increased from one side L of the axis O2 toward the other side R. It has a second convex curve shape C222 which is connected to the two concave curve shape C221 and whose diameter is increased toward the other side R while the inclination of the tangent to the axis O2 is gradually reduced.
Here, increasing or decreasing the inclination with respect to the axis O2 is indicated by the absolute value of the inclination with respect to the axis O2.

The second edge suppression shape E22 is connected to the tangent line of the second convex curve shape C222 in the vicinity of the maximum value of the polynomial in the other side R of the second convex curve shape C222, and the diameter gradually increases toward the other side R. It is said to have a shaped shape.
Further, it is preferable that the second edge suppression shape E22 is formed so that the inclination with respect to the axis O1 gradually increases from one side L toward the other side R.

In this embodiment, the first curve shape C21 and the second curve shape C22 are curves that can be defined by a cubic polymorphism, respectively, and the first curve shape C21 is changed from one side L to the other side R of the axis O1. The cubic polygon that defines the second curve shape C22 from the other side R to the one side L in the axis O2 direction is the same.
The polynomials constituting the first curve shape C21 and the second curve shape C22 shown in FIG. 7 are, for example, the cubic polynomials shown in FIG. 3B.
Further, the first edge suppression shape E21 and the second edge suppression shape E22 have a roll gap corresponding to an increase in the plate thickness of the solidified shell in the roll axis (axis lines O1, O2) direction with respect to the third-order polynomial shown in FIG. 3B. The distribution may be added so as to narrow, and the diameter of the roll may be increased as it approaches the end.
That is, the first curve shape C21 and the second curve shape C22 shown in FIG. 7 have, for example, the maximum value (neighborhood) in the cubic polynomial that defines the profile of the first convex curve shape C111 (C122) shown in FIG. 3B. It is a portion that goes from one side L to the other side R (from the other end side R to one end side L) as a starting point. The first edge suppression shape E21 and the second edge suppression shape E22 are connected to the tangent line in the vicinity of the maximum value and increase in diameter as they are separated from the first convex curve shape C111 (C122) by 20 mR (radius of curvature 20 m). ) Profile. For example, the amount of increase in the plate thickness of the solidified cell may be obtained in advance by an experiment.

Others are the same as those in the first embodiment, and thus the description thereof will be omitted.

Next, with reference to FIG. 8, the operation in manufacturing the cast strip in the second embodiment will be described.
FIG. 8 is a schematic view illustrating the operation when the casting strip S is manufactured by the twin drum type casting strip continuous casting facility 1.

(1) Before the start of casting, as shown in FIG. 8A, the first cooling drum R21 and the second cooling drum R22 are at positions facing each other in the axes O1 and O2 directions (for example, the first cooling drum R11). The second cooling drum R12 is arranged at a position where it is aligned in the width direction).
When starting casting, the first cooling drum R21 is moved in the direction of arrow F211 and the second cooling drum R22 is moved in the direction of arrow F221. As a result, the roll gap between the cooling drum R11 and the second cooling drum R12 changes.
(2) As shown in FIG. 8B, for example, the first cooling drum R21 and the second cooling drum R22 are close to each other in the axes O1 and O2 directions by the first convex curve shape C211 and the second convex curve shape C222. Stop at the position.
At this time, the first edge suppressing shape E21 and the second edge suppressing shape E22 are arranged near the end of the casting strip S21 at the start of casting so that the plate profile does not become thick even if a thick solidified shell is formed.
When molten steel (molten metal) is supplied to the molten metal storage section, the first convex curve shape C211 and the second convex curve shape C222 are close to each other, so that the thickness of the central portion in the plate width direction is thin and the plate width direction A cast strip S21 having a thick plate profile at the end, that is, a concave plate profile in the plate width direction recessed in the plate thickness direction is formed.
After the casting is started, the first cooling drum R21 is moved in the direction of the arrow F212, and the second cooling drum R22 is moved in the direction of the arrow F222.
(3) As shown in FIG. 8C, the first cooling drum R21 is moved in the direction of arrow F213 and the second cooling drum R22 is moved in the direction of arrow F223 from the start of casting until it reaches the time of steady casting. The casting strip S22 is cast while moving. As a result, the cast strip S21 changes in the plate profile direction in which the plate thickness at the center portion in the plate width direction is thick and the plate thickness at the end portion in the plate width direction is thin as the movement amount changes, that is, it is slightly concave in the plate width direction. A cast strip S22 having a plate profile of is formed.
As a result, the formation of recesses due to thermal expansion in the cast strip S22 is suppressed.
Further, the first edge suppressing shape E21 and the second edge suppressing shape E22 move to positions separated from the casting strip S22.
After that, the first cooling drum R21 and the second cooling drum R22 move in the arrow F213 direction and the arrow F223 direction, respectively, until the flying touch is started.
(4) When it reaches the time of steady casting, the movement of the first cooling drum R21 and the second cooling drum R22 is stopped as shown in FIG. 8 (D).
As a result, at the time of steady casting, the first cooling drum R21 and the second cooling drum R22 reach a steady state, the first profile and the second profile do not change, and the plate profile of the casting strip S23 becomes substantially uniform.
Further, in a steady state, when the cooling drum R20 is moved as shown in FIG. 8 (D), a concave (asymmetric in the axial direction) crown is attached to the cooling drum R20 to make the cast strip a desired plate crown, thereby causing thermal expansion. The impact is mitigated.
Due to this crown, changes as shown in FIG. 10 occur in the cooling drum from immediately after casting to the steady state, but as shown in FIG. 8 (B) immediately after the start of casting and as shown in FIG. 8 (D) in the steady state. , The change in the cooling drum is offset by moving the cooling drum R20.
Regarding the amount of movement of the above drum, a desired plate profile can be obtained from the relationship between the change in the cooling drum with the elapsed time after the start of casting obtained in advance and the plate profile of the thin-walled slab including the edge up. The profile of the cooling drum gap may be obtained, and the amount of movement in the roll axis direction that becomes the profile may be obtained geometrically. The change in the cooling drum may be obtained in advance by heat transfer calculation, or may be obtained by experiment in advance. For the plate profile of the thin-walled slab including the edge-up, the plate profile change of the thin-walled cast strip after the start of casting may be mathematically expressed in advance in correspondence with the time after the start of casting.
For example, the roll gap distribution in the roll axis direction geometrically offsets the thermal expansion amount of the roll during casting and the edge-up of the thin-walled slab, so that the first cooling drum R11 and the second cooling drum R12 The amount of movement should be calculated.

According to the twin drum type casting strip continuous casting apparatus 1 and the manufacturing method of the casting strip S according to the second embodiment, the same effect as that of the first embodiment can be obtained.
Further, since the pair of cooling drums R20 includes the first edge suppressing shape E21 and the second edge suppressing shape E22, even if a thick solidified shell is formed at the plate width end portion of the casting strip S at the start of casting, It is possible to suppress the occurrence of edge-up.

Further, according to the twin drum type casting strip continuous casting apparatus 1 and the method for manufacturing the casting strip S according to the second embodiment, the C warp of the casting strip S 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 cooling drums R10 and R20 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 surfaces of the cooling drums R10 and R20 is defined by a polynomial, the degree of the polynomial may be set arbitrarily. Further, it may be defined by a polynomial of degree 5 or higher.

For example, in the above embodiment, the case where the pair of cooling drums R10 and R20 have a profile of a cubic curve has been described, but the profile formed on the surface of the pair of cooling drums R10 and R20 is quaternary. It may be defined by a polynomial containing the above orders.

Further, in the above embodiment, for example, the case where the first curve shape and the second convex curve shape are defined by a polynomial has been described, but the case is defined by means other than the polynomial (for example, a set of numerical data). May be good. Further, any (part or all) 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, regarding the first curve shapes C11 and C21 and the second curve shapes C12 and C22, the first curve shapes C11 and C21 defined from one side and the second curve shapes C12 defined from the other side, The case where C22 is the same has been described, but whether or not the first curve shapes C11 and C21 defined from one side and the second curve shapes C12 and C22 defined from the other side are the same is arbitrarily set. be able to.

Further, in the above embodiment, the case where the first cooling drums R11 and R21 and the second cooling drums R21 and R22 move together has been described, but the first cooling drums R11 and R21 and the second cooling drums R21 and R22 have been described. Only one of them may move along the axes O1 and O2.

Further, in the above embodiment, the case where the twin drum type casting strip continuous casting apparatus 1 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. However, 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 PR21 and the second profile PR22 include the first edge suppressing shape E21 and the second edge suppressing shape E22 has been described, but the first edge suppressing shape E21 and the second Whether or not the edge suppression shape E22 is provided can be arbitrarily set.
Further, in the above embodiment, the case where the first profile PR21 and the second profile PR22 are 20 mR (radius of curvature 20 m) has been described, but the radius of curvature can be changed as appropriate, for example, a polynomial of degree 2 or higher. The profile of the first profile PR21 and the second profile PR22 can be arbitrarily set.
Further, for example, either one of the first profile PR21 and the second profile PR22 may be configured to include the first edge suppression shape E21 and the second edge suppression shape E22.

Further, in the above embodiment, the case where the molten metal is molten steel has been described, but it may be applied to a double-drum type thin-walled slab continuous casting apparatus using a molten metal other than molten steel such as aluminum and copper.

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.

In a comparative example, in a twin-drum type casting strip continuous casting apparatus according to the prior art, for each pair of cooling drums having a drum length of 1500 mm, the profile of each cooling drum is set to a concave profile (crown amount 0.5 mm / radius) over the entire length. By doing so, the cast strip was set to a plate crown of 30 μm (difference between the plate thickness at the center of the plate and the plate thickness 25 mm inside from the plate edge).
The pair of cooling drums have a fixed relative position in the axial direction in the axial direction.

As shown in FIG. 7, the example of the present invention is composed of a first cooling drum and a second cooling drum that form a pair of cooling drums. The polynomials constituting the first curve shape C21 and the second curve shape C22 shown in FIG. 7 are, for example, the cubic polynomials shown in FIG. 3B. The first edge suppression shape E21 and the second edge suppression shape E22 are connected to the tangent line near the maximum value of the third-order polynomial shown in FIG. 3B, and their diameters increase as they are separated from the first convex curve shape C111 (C122). It is a profile of 20 mR (radius of curvature 20 m).
The first cooling drum has a first convex curve shape in which the inclination of the tangent line with respect to the axis gradually increases while the diameter is reduced from one side of the axis toward the other side, and the first convex curve shape is connected to the other side. Therefore, a first profile including a first curved shape having a first concave curved shape in which the inclination of the tangent to the axis gradually decreases while the diameter is reduced is formed on the outer peripheral surface. Then, a first edge suppression shape was formed on one side of the first curve shape.
Further, the second cooling drum is connected to the second concave curve shape and the second concave curve shape in which the inclination of the tangent line with respect to the axis gradually increases while the diameter is increased from one side of the axis toward the other side. A second profile including a second curve shape having a second convex curve shape in which the slope of the tangent line with respect to the axis gradually decreases while the diameter is increased toward the outer peripheral surface is formed. Then, a second edge suppressing shape was formed on the other end side of the second curved shape.
In addition, the pair of cooling drums can be moved in the axial direction. Then, the plate profile change of the thin-walled casting strip after the start of casting obtained in advance by an experiment is mathematically expressed in correspondence with the time after the start of casting, and the relative positions of the pair of cooling drums in the axial direction are controlled based on the mathematical formula. The cast strip was moved and cast to a set plate profile.

Regarding the comparative example and the example of the present invention, the timing at which the plate breakage did not occur in the in-line mill when the flying touch was started was investigated.

In the comparative example, the flying touch can be started 30 seconds after the start of casting, and when the flying touch is started 30 seconds after the start of casting, an off gauge of about 40 m is generated.

In the example of the present invention, the flying touch can be started 10 seconds after the start of casting, and the off gauge of about 13 m or more is generated by starting the flying touch 10 seconds after the start of casting. That is, in the example of the present invention, the timing of the flying touch could be made earlier than that of the comparative example, and the off-gauge could be reduced to about 1/3 of that of the comparative example.

From the above, according to the present invention, it has been confirmed that in the double-drum type thin-walled thin-walled casting strip continuous casting equipment, the manufacturing cost can be realized by accelerating the timing of the flying touch and reducing the off-gauge of the casting strip.

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 time until the flying touch is shortened, the generation of off-gauge is suppressed, and the yield of the thin-walled slab is improved. It is industrially available because it can be used.

L One side R The other side S Cast 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, R20 Pair of cooling drums R11, R21 1st cooling roll R12, R22 2nd cooling roll PR11, PR21 1st profile C11, C21 1st curved shape E21 1st edge suppression shape PR12, PR22 2nd profile C111, C211 1 Convex curve shape C112, C212 1st concave curve shape C12, C22 2nd curve shape C121, C221 2nd concave curve shape C122, C222 2nd convex curve shape E22 2nd edge suppression shape 11 Dummy sheet 12 Protrusion part 13 Dummy bar 15 Metal molten metal storage part 20 Antioxidant device 30 Cooling device 40 First pinch roll 40A, 40B Position detection device R40A Upper pinch roll R40B Lower pinch roll 41 Housing 42A, 42B Roll chock 43A Upper rolling load detection device 43B Lower rolling load detection device 44 Electric Rolling device (rolling means)
50 In-line mill 51A, 51B Work roll 52A, 52B Intermediate roll 53A, 53B Backup roll 54 In-line mill control device 541 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 total 60 2nd pinch roll 81 Feed roll 82, 83 Tension roll 84 Deflector roll 70 Winding device

Claims (7)

A pair of cooling drums that are rotatable around an axis arranged parallel to each other and a metal molten metal storage portion formed by a side dam are injected with molten metal, and the pair of cooling drums face each other with their peripheral surfaces facing downward. This is a twin-drum type thin-walled slab continuous casting apparatus that produces thin-walled slabs by solidifying and growing the molten metal injected into the molten metal storage section on the peripheral surfaces of the pair of cooling drums.
The pair of cooling drums
A first convex curve shape in which the absolute value of the inclination of the tangent to the axis gradually increases while the diameter is reduced from one side of the axis toward the other, and a first convex curve shape connected to the first convex curve shape toward the other side. A first cooling drum having a first profile formed on the outer peripheral surface including a first concave curve shape having a first concave curve shape in which the absolute value of the inclination of the tangent line with respect to the axis gradually decreases while being reduced in diameter according to
A second concave curve shape in which the absolute value of the inclination of the tangent line with respect to the axis gradually increases while the diameter is increased from one side of the axis toward the other side, and a second concave curve shape connected to the second concave curve shape toward the other side. A second cooling drum having a second profile formed on the outer peripheral surface including a second convex curve shape having a second convex curve shape in which the absolute value of the inclination of the tangent line with respect to the axis gradually decreases while the diameter is increased according to the above.
With
The first cooling drum and the second cooling drum are configured to be relatively movable along the axis .
A first edge suppressing shape connected to the one side of the first curved shape and increasing in diameter toward the one side, and a first edge suppressing shape connected to the other side of the second curved shape toward the other side. Therefore , a twin-drum type thin-walled slab continuous casting apparatus including at least one of the second edge restraining shapes having an enlarged diameter . The twin drum type thin-walled slab continuous casting apparatus according to claim 1.
A twin-drum type thin-walled slab continuous casting apparatus, characterized in that at least one of the first curved shape and the second curved shape is defined by a polynomial. The twin drum type thin-walled slab continuous casting apparatus according to claim 1.
A double-drum type thin-walled slab continuous casting apparatus, wherein at least one of the first curved shape and the second curved shape is defined by a polynomial of degree 3 or higher. A first convex curve shape in which the absolute value of the inclination of the tangent to the axis gradually increases while the diameter is reduced from one side of the axis toward the other side, and a first convex curve shape connected to the first convex curve shape toward the other side. Therefore, a first cooling drum having 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 axis gradually decreases while the diameter is reduced, and a first cooling drum having a first profile formed on the outer peripheral surface.
A second concave curve shape in which the absolute value of the inclination of the tangent line with respect to the axis gradually increases while the diameter is increased from one side of the axis toward the other side, and a second concave curve shape connected to the second concave curve shape toward the other side. Therefore, a second cooling drum having a second profile including a second curved shape having a second convex curve shape in which the absolute value of the inclination of the tangent to the axis gradually decreases while the diameter is expanded, and a second cooling drum having a second profile formed on the outer peripheral surface.
Bei to give a,
A first edge suppressing shape connected to the one side of the first curved shape and increasing in diameter toward the one side, and a first edge suppressing shape connected to the other side of the second curved shape toward the other side. Therefore, a pair of cooling drums having at least one of the enlarged second edge suppression shapes, and
The metal molten metal is injected into the metal molten metal storage portions formed by the side dams arranged on both sides in the width direction of the pair of cooling drums, and the peripheral surfaces of the pair of cooling drums facing each other are rotated downward to cause the metal molten metal. The molten metal injected into the reservoir is solidified and grown on the peripheral surfaces of the pair of cooling drums, and thin-walled slabs are cast while the first cooling drum and the second cooling drum are relatively moved along the axis. A method for producing a thin-walled slab, which is characterized in that. The method for producing a thin-walled slab according to claim 4 .
A method for producing a thin-walled slab, which comprises using a pair of cooling drums defined by a polynomial for at least one of the first curved shape and the second curved shape. The method for producing a thin-walled slab according to claim 4 .
A method for producing a thin-walled slab, wherein at least one of the first curved shape and the second curved shape uses a pair of cooling drums defined by a polynomial of degree 3 or higher. The method for producing a thin-walled slab according to any one of claims 4 to 6 .
Controlling the relative movement amount of the first cooling drum and the second cooling drum in the axial direction based on the change in the cooling drum and the plate profile of the thin-walled slab obtained in advance with the elapsed time after the start of casting. A method for producing a thin-walled slab, which is characterized by.

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