JP2018061998A - Twin drum type continuously casting device for thin cast piece and manufacturing method for thin cast piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a twin-drum type continuously casting device for a thin cast piece, which is able to improve thin cast piece yield when manufacturing a thin cast piece while rotating a pair of cooling drums, and to provide a manufacturing method for a thin cast piece.SOLUTION: A twin-drum type continuously casting device for a thin cast piece is for manufacturing a thin cast piece from molten metal by rotating a pair of cooling drums R10. The pair of cooling drums R10 comprises: a first cooling drum R11 in which a first profile PR11 is formed including a first projecting curved shape C111 and a first recessed curved shape C112 that are reduced in diameter from one side L to the other side R of an axis O1; and a second cooling drum R12 in which a second profile PR12 is formed including a second recessed curved shape C121 and a second projecting curved shape C122 increased in diameter from one side L to the other side R of an axis O2. The first cooling drum R11 and the second cooling drum R12 move relative to each other along the axes O1, O2.SELECTED DRAWING: Figure 3A

Description

  The present invention relates to a twin-drum type thin cast piece continuous casting apparatus including a pair of continuous casting cooling drums, and a method for producing a thin cast piece.

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

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

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

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

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

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

  In the twin-drum type thin cast strip continuous casting equipment, the cooling drum is generally at a low temperature before the casting is started. When casting starts, the cooling drum is heated by 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 referred to as steady casting, the temperature of the cooling drum during steady casting is referred to as steady temperature, and such a state is referred to as a steady state.

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

  FIG. 9 is a conceptual diagram showing a change with the elapsed time after the casting of the cooling drum profile and the casting strip plate profile when the casting strip is manufactured by the conventional twin-drum type casting strip continuous casting equipment. The plate profile of the cast strip shows the case where the cooling drum is cast without shifting and the reduction in the in-line mill is not performed.

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

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

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

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

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

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

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

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

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

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

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

  The time required to reach FIG. 10C from FIG. 10A varies depending on the steel type (melting temperature) of the molten metal, the thickness of the casting strip, the rotational speed of the cooling drum, and the cooling efficiency. 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 is a combination of the crown change due to the thermal expansion of the cooling drum and the edge-up change due to uneven cooling of the cooling drum, as shown in FIG. Thus, immediately after the start of casting, as in S301 in FIG. 11A, when a while has elapsed after the start of casting, as in S302 in FIG. 11B, in a steady state, as in S303 in FIG. 11C. It becomes the plate profile of the cast strip.

  When a cast strip cast by a twin drum type thin cast strip continuous casting facility is rolled by an in-line mill, the temperature of the cast strip at the inlet side of the in-line mill is about 1000 ° C. Although a little plate crown adjustment is possible, the in-line mill has a crown control capability that corresponds to a cast strip of a plate profile as shown in FIGS. 11 (A) and 11 (B). Not.

  On the other hand, when the amount of crown is adjusted by rolling a cast strip of a plate profile as shown in FIG. 11 with a large force by an in-line mill, the plate width central portion and the plate width end portion are increased in the longitudinal direction. Then, since the middle elongation at the center portion of the plate width and the end elongation at the end portion of the plate width are extremely increased, the cast strip is easily broken.

Also, the casting strip is started in the in-line mill, the casting strip is rolled, and until the desired thickness is reached in the in-line mill, the casting strip is cut off as a scrap after being processed as off-gauge (out of thickness). It is common to be processed.
As a result, the off-gauge of the cast strip is a major cause of an increase in manufacturing cost due to a decrease in the yield of the cast strip.
In addition, the edge-up and convex crown may cause instability at the time of winding and C warp (warp in the plate width direction) when the wound cast strip is rewound in the next process, and so on. There was also a demand for measures to reduce the convex crown.

  The off-gauge of such a cast strip is caused by rolling the cast strip as shown in FIGS. 11A and 11B, and casts a cast strip that can start a flying touch at an early timing. 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 in advance with a heater, and the temperature distribution of the cooling drum at the start of casting It is conceivable to reduce the bias.

JP 2000-343103 A

  However, when starting casting by connecting dummy sheets in a twin drum type thin cast strip continuous casting facility, the cooling drum is not rotating when the dummy sheet is connected, and the cooling drum is heated uniformly over the entire circumference. It is difficult to do. Furthermore, since the heat that escapes increases at the contact portion of the cooling drum with the dummy sheet, 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. Causes new and fluctuating problems.

  Therefore, there is a need for a technique that can shorten the time to flying touch when manufacturing a thin cast piece while rotating a pair of cooling drums with a twin drum type thin cast piece continuous casting apparatus.

  The present invention has been made in view of such a problem, and a pair of cooling drums is formed by injecting a molten metal into a molten metal storage portion formed by a pair of cooling drums and side weirs that can be rotated. When producing thin cast slabs by solidifying and growing the molten metal on the peripheral surface of the cooling drum while rotating the machine, the time to flying touch is shortened to suppress the occurrence of off-gauge and increase the yield. It is an object of the present invention to provide a twin-drum type thin-walled continuous casting apparatus and a method for manufacturing a thin-walled slab, which can improve the manufacturing cost of the thin-walled slab.

Accordingly, the inventors of the present invention store the molten metal in a molten metal storage section formed by a pair of cooling drums and side weirs that are rotatable, and rotate the pair of cooling drums while rotating the pair of cooling drums. As a result of earnest research on the technology to shorten the time from the start of casting until the off-gauge does not occur in the case of producing a thin cast slab by solidifying and growing on the peripheral surface of the cooling drum, It has been found that it is effective to make the plate profile of the thin cast slab sent to the in-line mill uniform, and the following means are effective.
(1) When the pair of cooling drums are moved relative to each other along the axis, a portion having a deep concave shape (a central portion in the width direction) and a portion having a shallow concave shape (a portion close to the end in the width direction) are combined. Even if the influence of the concave shape is offset and the depth of the concave shape changes depending on the temperature of the cooling drum, a thin cast slab having a plate profile with a small crown amount at the center portion of the plate width is efficiently produced. be able to.
(2) When manufacturing the pair of cooling drums relative to each other along the axis, by reducing the distance between the pair of cooling drums for the portion that forms the plate width end of the thin cast piece at the start of casting, Even if the thickness of the solidified shell is increased, the amount of edge-up can be effectively reduced.

In order to solve the above problems, the present invention proposes the following means.
According to the first aspect of the present invention, molten metal is injected into a molten metal reservoir formed by a pair of cooling drums and side weirs that are rotatable around axes arranged parallel to each other, and the pair of cooling drums A twin-drum type thin casting in which thin drums are produced by rotating the drums with their circumferential surfaces facing each other downward and solidifying and growing the molten metal injected into the molten metal reservoir on the circumferential surfaces of the pair of cooling drums. In the continuous continuous casting apparatus, the pair of cooling drums has a first convex curve shape in which a slope of a tangent to the axis gradually increases while being reduced in diameter from one side of the axis toward the other side, and the first A first profile including a first curved shape having a first concave curved shape connected to a convex curved shape and having a diameter that gradually decreases toward the other side, while the slope of the tangent to the axis gradually decreases. A first cooling drum formed on the outer peripheral surface, a second concave curve shape in which the diameter of the tangential line with respect to the axis gradually increases while increasing in diameter from one side of the axis toward the other side, and the second A second profile including a second curved shape having a second curved shape, which is connected to a concave curved shape and is enlarged in diameter toward the other side while gradually decreasing the inclination of the tangent to the axis, is formed on the outer peripheral surface. The first cooling drum and the second cooling drum are configured to be relatively movable along the axis.

  The invention according to claim 6 is a method for producing a thin cast slab, wherein the first convex curve shape in which the inclination of the tangential line with respect to the axis gradually increases while being reduced in diameter from one side of the axis toward the other side. A first profile including a first curve shape having a first concave curve shape that is connected to the first convex curve shape and is reduced in diameter toward the other side while gradually decreasing a slope of a tangent to the axis. A first cooling drum formed on the outer peripheral surface, a second concave curved shape in which the diameter of the tangential line with respect to the axis gradually increases while increasing in diameter from one side of the axis toward the other side, and the second concave A second pro that includes a second curved shape having a second convex curved shape connected to the curved shape and having a diameter gradually increasing toward the other side and gradually decreasing the slope of the tangent to the axis. A molten metal is supplied to a molten metal reservoir formed by a pair of cooling drums including a second cooling drum having a fill formed on the outer peripheral surface, and side weirs disposed on both sides in the width direction of the pair of cooling drums. The molten metal injected into the molten metal reservoir is solidified and grown on the peripheral surfaces of the pair of cooling drums, and the pair of cooling drums are rotated on the axis. A thin cast slab is cast while the first cooling drum and the second cooling drum are moved relative to each other.

According to the twin drum type thin cast slab continuous casting apparatus and the thin cast slab manufacturing method according to the present invention, the first profile including the first curved shape having the first convex curved shape and the first concave curved shape is the outer peripheral surface. And a second cooling drum having a second profile including a second curved shape having a second concave curve shape and a second convex curve shape formed on the outer peripheral surface. Since the molten metal stored in the molten metal storage section is solidified and grown while relatively moving the first cooling drum and the second cooling drum along the axis, the thin cast piece is cast. The unevenness formed on the thin cast slab after the start can be reduced, and the time until the flying touch can be shortened.
As a result, the yield can be improved by reducing the occurrence of off-gauge in the production of thin cast slabs.

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

  The invention according to claim 2 is the twin-drum type thin cast slab continuous casting apparatus according to claim 1, wherein at least one of the first curve shape and the second curve shape is defined by a polynomial. It is characterized by being.

  The invention according to claim 7 is the thin-walled slab manufacturing method according to claim 6, wherein at least one of the first curved shape and the second curved shape is a pair defined by a polynomial expression. The cooling drum is used.

According to the twin drum thin cast slab continuous casting apparatus and the thin cast slab manufacturing method 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 polynomial expression. Therefore, the first curve shape and the second curve shape can be defined efficiently and reliably, 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, that at least one of the first curve shape and the second curve shape is defined by a polynomial means that the first curve shape and the second curve shape are both defined by a polynomial, The case where only one of the curve shape and the second curve shape is defined by a polynomial is included. If the plate profile on one side and the other side of the thin cast slab is not symmetrical in the plate width direction (from one side to the other side and one side from the other side in the axial direction), It may be effective that the two-curved shape is asymmetric in the plate width direction. On the other hand, when it is symmetric in the plate width direction, it is preferable that the first curve shape and the second curve shape are symmetric in the plate width direction.

  Invention of Claim 3 is a twin drum type thin wall cast slab continuous casting apparatus of Claim 1, Comprising: At least any one of the said 1st curve shape and the said 2nd curve shape is 3rd order or more It is defined by a polynomial.

  Invention of Claim 8 is a manufacturing method of the thin cast slab of Claim 6, Comprising: At least any one of the said 1st curve shape and the said 2nd curve shape is defined by the polynomial more than a third degree. A pair of cooling drums is used.

  According to the twin drum type thin wall cast continuous casting apparatus and the thin wall cast manufacturing method according to the present invention, at least one of the first curve shape and the second curve shape is defined by a polynomial having a cubic or higher order. Since the pair of cooling drums are 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 cubic polynomial means that both the first curve shape and the second curve shape are defined by a third-order polynomial 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.

  The invention according to claim 4 is the twin-drum type thin cast piece continuous casting apparatus according to any one of claims 1 to 3, wherein the one side is connected to the one side of the first curved shape. At least one of a first edge suppression shape expanded in diameter toward the side and a second edge suppression shape connected to the other side of the second curved shape and expanded in diameter toward the other side It is characterized by providing.

  Invention of Claim 9 is a manufacturing method of the thin wall cast piece of any one of Claim 6 to 8, Comprising: It connects to the said one side of the said 1st curve shape, and goes to the said one side The first edge suppression shape expanded in diameter according to the above, and at least one of the second edge suppression shape connected to the other side of the second curved shape and expanded toward the other side A pair of cooling drums is used.

  According to the twin drum type thin cast slab continuous casting apparatus and the thin cast slab manufacturing method according to the present invention, the pair of cooling drums includes at least one of the first edge restraining shape and the second edge restraining shape. Therefore, even if a thick solidified shell is formed at the plate width end portion of the thin plate slab at the start of casting, it is possible to suppress the occurrence of edge-up.

  In this specification, the pair of cooling drums includes at least one of the first edge suppression shape and the second edge suppression shape. The pair of cooling drums includes both the first edge suppression shape and the second edge suppression shape. In addition to the case where it is provided, the pair of cooling drums includes a case where only one of the first edge suppression shape and the second edge suppression shape is provided.

  A fifth aspect of the present invention is the twin-drum type thin-walled continuous casting apparatus according to any one of the first to fourth aspects, wherein the thin-walled casting with the elapsed time after the start of casting acquired in advance. The relative movement amount of the first cooling drum and the second cooling drum in the axial direction is controlled based on the change in the plate profile of the piece and the plate profile of the thin cast piece to be cast.

  Invention of Claim 10 is a manufacturing method of the thin cast piece of any one of Claims 6-9, Comprising: The change of the said cooling drum with the elapsed time after the casting start acquired previously, 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 cast slab.

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

In this specification, acquiring the change in the cooling drum with the elapsed time after the start of casting and the plate profile of the thin-walled slab in advance includes not only the case of acquiring by experiment, but also the case of acquiring by a method other than the experiment such as simulation. Shall be.
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. Shall be included.

  According to the twin drum type thin cast slab continuous casting apparatus and the thin cast 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 cast slab. it can. As a result, the manufacturing cost of the thin slab can be reduced.

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

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

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

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

A feed roll 81 is disposed between the twin drum cast strip continuous casting equipment 10 and the first pinch roll 30.
A tension roll 82 is disposed between the first pinch roll 40 and the inline mill 50, and a tension roll 83 is disposed between the inline mill 50 and the second pinch roll 60.
Further, a deflector roll 84 is disposed between the second pinch roll 60 and the winding device 70.

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

  The pair of cooling drums R10 includes a first cooling drum R11 and a second cooling drum R12. The first cooling drum R11 and the second cooling drum R12 correspond to the plate thickness (internal quality) of the cast strip S to be manufactured. (The distance between the rotation axes) can be adjusted.

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

  Further, the moving amounts of the first cooling drum R11 and the second cooling drum R12 are set based on, for example, the change in the pair of cooling drums R10 with the elapsed time after the start of casting obtained by experiment and the plate profile of the casting strip S. ing. In addition, you may set based on simulation irrespective of an experiment, and it is good also as a structure controlled in real time based on the data acquired by the board profile form.

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

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, a first curved shape C11, and the first curved shape C11 is first diameter-expanded and then reduced in diameter from the one side L to the other side R of the axis O1. It has a convex curve shape C111 and a first concave curve shape C112 that is connected to the first convex curve shape C111 and is once reduced in diameter and then expanded in diameter toward the other side R. The reduced diameter and the expanded diameter in the first curve shape C11 are set so that the shape gradually changes gradually.

The first curved line shape C11 will be described in more detail. The first convex curved line shape C111 in which the inclination of the tangent line with respect to the axis O1 gradually increases while being reduced in diameter as it goes from the one side L to the other side R of the axis O1, The first concave curve shape C112 is connected to the one convex curve shape C111, and the diameter of the tangent line with respect to the axis O1 gradually decreases while decreasing in diameter toward the other side R.
Here, the fact that the inclination with respect to the axis O1 increases or decreases 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, a second curved line shape C12, and the second curved line shape C12 is first reduced in diameter and then expanded in diameter from the one side L to the other side R of the axis O2. It has a concave curve shape C121 and a second convex curve shape C122 that 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 in the second curved line shape C12 are set so that the shape gradually changes gradually.

The second curved line shape C12 will be described in more detail. The second concave curved line shape C121 in which the inclination of the tangent line with respect to the axis O2 is gradually increased while the diameter is increased from the one side L to the other side R of the axis O2, The second convex curve shape C122 is connected to the two concave curve shape C121 and the diameter of the tangential line with respect to the axis O2 gradually decreases while increasing in diameter toward the other side R.
Here, the fact that the inclination with respect to the axis O2 increases or decreases 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 third-order polynomial that is defined toward the left side and the third-order polynomial that defines the second curve shape C12 from the other side R toward the one side L in the direction of the axis O2 are the same.
The polynomial defining the first curved line shape C11 from one side L to the other side R of the axis O1 is different from the polynomial defining the second curved line shape C12 from the other side R in the direction of the axis O2 to the one side L ( (Not identical).

Hereinafter, referring 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 (the first profile PR11, the first profile PR11, 2 profile PR12) will be described. FIG. 3B is a diagram illustrating an example of a third-order polynomial (or a fourth-order polynomial) related to the first profile PR11 of the first cooling drum R11.
As shown in FIG. 3B, the drive side end on one side L of the first cooling drum R11 is set to 0, the work side end on the other side R is set to 1.0, and the axial center position (0.5) is set. A description will be given assuming that the crown is zero.

In this embodiment, the first curve shape C11 (second curve shape C12) can be defined by a third-order polynomial or a fourth-order polynomial (third-order or higher polynomial), as shown in FIG. 3B.
Further, for example, a third-order or higher-order term defining the first curved line shape C11 from one side L of the axis O1 toward the other side R, and the second curved line shape C12 from the other side R of the axis O2 to the one side L. The third-order or higher-order polynomials defined toward it are the same.

The crown (first profile PR11) of the first cooling drum R11 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.
As for a specific method of obtaining the polynomial, for example, when the gap between the first cooling roll R11 and the second cooling roll R12 is set to a desired thickness of the thin cast slab, the roll axis before the movement in the roll axis direction is used. When the roll gap distribution in the direction geometrically matches the desired profile of the thin cast slab and is moved in the roll axis direction, the maximum expansion amount of the roll gap is the first cooling roll R11 or What is necessary is just to determine the coefficient of each term so that it may become equal to or more than the amount of thermal expansion in the radial direction in the steady state of the second cooling roll R12. 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 axial direction before the start of casting and in a steady state is measured. You may ask for it.

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

<4th order polynomial>
The crown of the first cooling drum R11 can be expressed by, for example, the following fourth-order polynomial.
R14 (X) = A14 × X ⁴ + B14 × X ³ + C14 × X ² + D14 × X + E14
A14 = 6002.3, B14 = 5644.9, C14 = 396.85,
D14 = 250.97, E14 = 9.7902
Here, R14 (X) represents the crown amount (numerical value per radius) from the axis O41, and X represents the position in the axial direction.

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

  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 drum length (width) of the pair of cooling drums R10 are not limited to these.

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

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

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

  As shown in FIG. 4, the first pinch roll 40 includes, for example, position detection devices 40A and 40B, an upper pinch roll R40A, a lower pinch roll R40B, a housing 41, roll chocks 42A and 42B, and an upper rolling load detection. A device 43A, a lower rolling load detection device 43B, and an electric reduction device (reduction means) 44 are provided. Also, for example, a hydraulic pressure reduction cylinder is installed in a housing positioned above the backup roll chock above the casting strip.

  The upper and lower pinch rolls R40A, R40B have hollow channels formed therein, and can be cooled by circulating a cooling medium (for example, cooling water). The upper and lower pinch rolls R40A and R40B have, for example, a roll diameter of 400 mm and a roll trunk length (width) of 2000 mm.

Further, the upper and lower pinch rolls R40A, R40B are arranged in the housing 41 via roll chocks 42A, 42B, and are rotated by a motor (not shown).
The upper pinch roll R40A is connected to a reduction device (reduction means) 44 via an upper rolling load detection device 43A, and the lower pinch roll R40B is connected to the lower rolling load detection device 43B.

  When the electric pinch roll 44 rolls down the upper pinch roll R40A, it detects the rolling load of the upper and lower pinch rolls R40A and R40B, and generates a tension between the first pinch roll 40 and the inline mill 50 on the casting strip S. It has become.

  Further, the tension generated between the first pinch roll 40 and the inline mill 50 is measured by a tension roll 82 provided between the first pinch roll 40 and the inline mill 50, and between the first pinch roll 40 and the inline 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 a device that rolls the cast strip S to reduce the cast strip S to a desired plate thickness. In this embodiment, the in-line mill 50 is a six-high rolling mill.
As shown in FIGS. 1 and 2, the in-line mill 50 includes work rolls 51A and 51B that are opposed to each other, intermediate rolls 52A and 52B disposed behind the work rolls 51A and 51B, and intermediate rolls 52A and 52B. Are provided with backup rolls 53A and 53B, an in-line mill control device 54, and a thickness gauge 55.

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

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

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

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

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

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

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

  The winding device 70 receives the cast strip S rolled by the in-line mill 50 and sent out from the second pinch roll 60 via the deflector roll 84 and winds it in a coil shape.

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

Next, with reference to FIG. 6, the effect | action at the time of manufacturing a cast strip with the twin drum type cast strip continuous casting installation 1 is demonstrated.
FIG. 6 is a schematic view for explaining the operation when the casting strip S is manufactured by the twin drum type casting strip continuous casting equipment 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 opposed to each other in the directions of the axes O1 and O2 (for example, the first cooling drum R11 and the first cooling drum R11). The second cooling drum R12 is arranged at a position where the second cooling drums R12 are 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. Thereby, 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, the first convex curve shape C111 and the second convex curve shape C122 are close to each other in the directions of the axes O1 and O2. Stop at position.
And molten steel (metal melt) is supplied to the metal melt storage part comprised by 1st cooling drum R11 and 2nd cooling drum R12.
In the supplied molten steel, the first convex curve shape C111 and the second convex curve shape C122 are close to each other, so that the plate thickness in the center portion in the plate width direction is thin and the plate thickness in the plate width direction end portion is thick. A casting strip S11 having a profile, that is, a concave plate profile in the plate width direction recessed in the plate thickness direction, is formed.
After starting casting, the first cooling drum R11 is moved in the direction of arrow F112, and the second cooling drum R12 is moved in the direction of arrow F122.
(3) From the start of casting until reaching the time of steady casting, 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. 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 in the center portion in the plate width direction is thicker and the plate thickness in the plate width direction end portion is thin as the amount of movement changes, that 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 the arrow F113 and the arrow F123, respectively, until the set timing at which the inline mill 50 starts the flying touch.
(4) When the steady casting is reached, the movement of the first cooling drum R11 and the second cooling drum R12 is stopped as shown in FIG. 6 (D).
As a result, at the time of steady casting, the first cooling drum R11 and the second cooling drum R12 reach a 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 casting strip is moved as shown in FIG. 6D, a concave (asymmetrical in the axial direction) crown is attached to the cooling drum R10 so that the cast strip has a desired plate crown. Impact is mitigated.
With this crown, a change as shown in FIG. 10 occurs in the cooling drum immediately after casting until the steady state, but as shown in FIG. 6B immediately after the start of casting, as shown in FIG. 6D in the steady state. The change in the cooling drum is canceled by moving the cooling drum R10.
Regarding the amount of movement of the above drum, the profile of the cooling drum gap that gives a desired plate profile is 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. What is necessary is just to obtain | require geometrically the moving amount | distance in the roll axis direction which calculates | requires and becomes the profile. The change of the cooling drum may be obtained in advance by heat transfer calculation, or may be obtained in advance by experiments. The plate profile of the thin-walled slab may be preliminarily formulated by experiment in accordance with the plate-profile change of the thin-walled cast strip after the start of casting corresponding to the time after the start of casting.
For example, the movement amount 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 thermal expansion amount of the roll being cast.

According to the twin-drum type casting strip continuous casting apparatus 1 and the manufacturing method of the casting strip S according to the first embodiment, unevenness formed in the casting strip S after the start of casting due to the influence of thermal expansion of the cooling drum is reduced. The time until the flying touch can be shortened by reducing the size.
As a result, it is possible to reduce the occurrence of off-gauge in the production of the cast strip S and improve the yield.

According to the twin drum type cast strip continuous casting apparatus 1 and the method for manufacturing the cast strip S according to the first embodiment, the first curved shape C11 and the second curved shape C12 are defined by a polynomial having a cubic or higher order. The first curve shape C11 and the second curve shape C12 can be easily and efficiently defined, and the 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 twin-drum type casting strip continuous casting apparatus 1 and the manufacturing method of the casting strip S according to the first embodiment, 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. The amount of movement of the first cooling drum R11 and the second cooling drum R12 in the directions of the axes O1 and O2 is controlled on the basis of the plate profile of the casting strip S, so that the casting strip S with less unevenness can be 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, 7, and 8. 1, 2, 4, and 5 are the same as those in the first embodiment, and a description thereof is omitted. FIG. 7 is a diagram illustrating a schematic configuration of a cooling drum according to the second embodiment. 1, 2, and 7, a symbol R <b> 20 indicates a pair of cooling drums.

  The second embodiment is an example 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 the thermal expansion of the cooling drum, but the edge caused by the solidification and cooling of the casting strip. The purpose is to get a big effect on up.

The pair of cooling drums R20 includes a first cooling drum R21 and a second cooling drum R22. The distance between the first cooling drum R21 and the second cooling drum R22 (corresponding to the rotation shaft) is made to correspond to the plate thickness of the casting strip S. (Distance between 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 each other in the directions of arrows F21 and F22 along the drum width direction (axis lines O1 and O2). ing.

As shown in FIG. 7, the first cooling drum R <b> 21 has a first profile PR <b> 21 on the outer peripheral surface along the axis O <b> 1.
The first profile PR21 includes, for example, a first curve shape C21 and a first edge suppression shape E21.

  The first curved line shape C21 is connected to the first convex curved line shape C211 and the first convex curved line shape C211 that are once expanded from the one side L to the other side R of the axis O1. A first concave curved line shape C212 that is once reduced in diameter and then expanded in diameter toward R is provided. The reduced diameter and the expanded diameter in the first curved shape C21 are set so that the shape gradually changes gradually.

The first curved line shape C21 will be described in more detail. A first convex curved line shape C211 in which the inclination of the tangent line with respect to the axis O1 gradually increases while being reduced in diameter from the one side L to the other side R of the axis O1, A first convex curve shape C211 is connected to the first convex curve shape C211 and the first concave curve shape C212 is gradually reduced in diameter toward the other side R while the inclination of the tangent to the axis O1 gradually decreases.
Here, the fact that the inclination with respect to the axis O1 increases or decreases 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 on one side L of the first convex curve shape C211, and from the other side R toward the one side L. Therefore, the shape is gradually expanded. That is, the diameter is gradually reduced from one side L to the other side R.
Further, the first edge suppression shape E21 is formed, for example, such that the inclination with respect to the axis O1 gradually decreases from the 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 curve shape C22 and a second edge suppression shape E22.

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

The second curved line shape C21 will be described in more detail. A second concave curved line shape C221 in which the diameter of the tangent line with respect to the axis O2 gradually increases while increasing in diameter from the one side L to the other side R of the axis O2, The second convex curve shape C222 is connected to the two concave curve shape C221, and the diameter of the tangential line with respect to the axis O2 gradually decreases while increasing in diameter toward the other side R.
Here, the fact that the inclination with respect to the axis O2 increases or decreases 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 of the second convex curve shape C222 in the vicinity of the maximum value of the polynomial on the other side R of the second convex curve shape C222, and gradually increases in diameter toward the other side R. It is made the shape.
In addition, it is preferable that the second edge suppression shape E22 is formed such that the inclination with respect to the axis O1 gradually increases from the 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 polynomial, respectively, and the first curve shape C21 is changed from one side L to the other side R of the axis O1. The third-order polynomial defined toward the left side and the third-order polynomial defining the second curve shape C22 from the other side R toward the one side L in the direction of the axis O2 are the same.
In addition, the polynomial which comprises 1st curve shape C21 and 2nd curve shape C22 shown in FIG. 7 is taken as the 3rd order polynomial shown in FIG. 3B, for example.
Further, the first edge restraining shape E21 and the second edge restraining shape E22 have a roll gap corresponding to the increase in the thickness of the solidified shell in the roll axis (axis O1, O2) direction with respect to the cubic polynomial shown in FIG. 3B. What is necessary is just to add the distribution which becomes narrow and to expand a roll diameter as it approaches an edge part.
That is, the first curve shape C21 and the second curve shape C22 shown in FIG. 7 are, for example, local maximum values (neighbors) in a cubic polynomial defining the profile of the first convex curve shape C111 (C122) shown in FIG. 3B. The starting point is a portion from one side L toward the other side R (from the other end side R to one end side L). The first edge suppression shape E21 and the second edge suppression shape E22 are connected to a tangent line in the vicinity of the maximum value, and increase in diameter as the distance from the first convex curve shape C111 (C122) increases. ) Profile. The increase in thickness of the coagulation cell may be obtained in advance by experiments, for example.

  Since others are the same as that of 1st Embodiment, description is abbreviate | omitted.

Next, with reference to FIG. 8, the effect | action at the time of manufacturing a casting strip in 2nd Embodiment is demonstrated.
FIG. 8 is a schematic view for explaining the operation when the casting strip S is manufactured by the twin drum type casting strip continuous casting equipment 1.

(1) Before the start of casting, as shown in FIG. 8 (A), the first cooling drum R21 and the second cooling drum R22 are opposed to each other in the directions of the axes O1 and O2 (for example, the first cooling drum R11 and the first cooling drum R11). The second cooling drum R12 is arranged at a position where the second cooling drums R12 are 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. Thereby, 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, and the first convex curve shape C211 and the second convex curve shape C222 are close to each other in the directions of the axes O1 and O2. Stop at position.
At this time, the first edge suppression shape E21 and the second edge suppression shape E22 are arranged in the vicinity of 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 (metal melt) is supplied to the molten metal reservoir, the first convex curve shape C211 and the second convex curve shape C222 are close to each other. 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 starting casting, the first cooling drum R21 is moved in the direction of arrow F212, and the second cooling drum R22 is moved in the direction of arrow F222.
(3) From the start of casting until reaching the time of steady casting, 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. The casting strip S22 is cast while moving. As a result, the casting strip S21 changes in the plate profile direction in which the plate thickness in the center portion in the plate width direction is thicker and the plate thickness in the end portion in the plate width direction is thin as the amount of movement changes, that is, slightly concave in the plate width direction. A cast strip S22 having the following plate profile is formed.
As a result, the formation of a recess due to thermal expansion in the casting strip S22 is suppressed.
Moreover, the 1st edge suppression shape E21 and the 2nd edge suppression shape E22 move to the position which remove | deviated from the casting strip S22.
Thereafter, the first cooling drum R21 and the second cooling drum R22 move in the directions of the arrow F213 and the arrow F223, respectively, until the flying touch is started.
(4) When the steady casting is reached, the movement of the first cooling drum R21 and the second cooling drum R22 is stopped as shown in FIG.
As a result, at the time of steady casting, the first cooling drum R21 and the second cooling drum R22 reach 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 movement is performed as shown in FIG. 8D, a concave (asymmetrical in the axial direction) crown is attached to the cooling drum R20 so that the cast strip has a desired plate crown. Impact is mitigated.
Due to this crown, a change as shown in FIG. 10 occurs in the cooling drum immediately after casting until the steady state, but as shown in FIG. 8B immediately after the start of casting, as shown in FIG. 8D in the steady state. The change in the cooling drum is canceled by moving the cooling drum R20.
Regarding the amount of movement of the drum, 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 acquired in advance and the plate profile of the thin cast slab including the edge up. What is necessary is just to obtain | require the profile of a cooling drum gap | interval, and to obtain | require geometrically the moving amount | distance in the roll axial direction which becomes the profile. The change of the cooling drum may be obtained in advance by heat transfer calculation, or may be obtained in advance by experiments. The plate profile of the thin-walled slab including the edge-up may be mathematically expressed in advance in accordance with the time after the start of casting the plate profile change of the thin-walled cast strip after the start of casting.
For example, the roll gap distribution in the roll axial direction geometrically cancels out the thermal expansion amount of the roll being cast and the edge-up of the thin slab, so that the first cooling drum R11 and the second cooling drum R12 What is necessary is just to calculate the amount of movement.

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 effects as those of the first embodiment can be obtained.
In addition, since the pair of cooling drums R20 includes the first edge suppression shape E21 and the second edge suppression shape E22, even if a thick solidified shell is formed at the plate width end of the casting strip S at the start of casting, The occurrence of edge up can be suppressed.

  Moreover, according to the twin drum type cast strip continuous casting apparatus 1 and the method for manufacturing the cast strip S according to the second embodiment, the C warpage of the cast strip S can be reduced.

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

  For example, in the above-described embodiment, the case where the pair of cooling drums R10 and R20 has a profile including the first curve shape and the second curve shape defined by a polynomial of third or higher order has been described. When the profile formed on the surface of each of the cooling drums R10 and R20 is defined by a polynomial, the order of the polynomial may be arbitrarily set. Further, it may be defined by a polynomial of 5th order or higher.

  For example, in the above-described embodiment, the case where the pair of cooling drums R10 and R20 has a cubic curve profile has been described. However, the profile formed on the surface of the pair of cooling drums R10 and R20 is quaternary. You may define with the polynomial containing the above degree.

  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. However, the first curve shape and the second convex curve shape may be defined by means other than a polynomial (for example, a set of numerical data). Also good. Moreover, you may define any one (part or all) of a 1st convex curve shape, a 1st concave curve shape, a 2nd concave curve shape, and a 2nd curve shape other than a polynomial.

  Moreover, in the said embodiment, regarding 1st curve shape C11, C21 and 2nd curve shape C12, C22, 1st curve shape C11, C21 defined from one side and 2nd curve shape C12 defined from the other side, Although the case where C22 is the same has been described, 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.

  In the above embodiment, the case where the first cooling drums R11, R21 and the second cooling drums R21, R22 move together has been described. However, the first cooling drums R11, R21 and the second cooling drums R21, R22 Only one of them may be configured to move along the axes O1 and O2.

  In the above-described embodiment, the case where the twin-drum type casting strip continuous casting apparatus 1 uses the dummy sheet 11 when starting casting of the casting strip S has been described. However, this is a case where no dummy sheet is used. However, the present invention can be applied to a twin-drum type casting strip continuous casting apparatus in which the profile of a pair of cooling drums thermally expands with time.

Moreover, in the said embodiment, although 1st profile PR21 and 2nd profile PR22 demonstrated the case provided with 1st edge suppression shape E21 and 2nd edge suppression shape E22, 1st edge suppression shape E21, 2nd was demonstrated. Whether or not the edge suppression shape E22 is provided can be arbitrarily set.
In the above-described embodiment, the case where the first profile PR21 and the second profile PR22 are 20 mR (curvature radius 20 m) has been described. However, the radius of curvature can be appropriately changed. The profiles of the first profile PR21 and the second profile PR22 can be arbitrarily set.
Further, for example, 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.

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

Examples of the present invention will be described below.
The example was implemented in the manufacturing process of the casting strip provided with the structure similar to FIG. The cast strip used in the examples has a plate thickness of 2 mm and a plate width of 1200 mm.
The acceleration rate of the cooling drum from the start of casting is 150 m / min / 30 seconds, and the rotation speed of the cooling drum in the steady casting state is 150 m / min.
In the in-line mill, rolling with a reduction rate of 30% is performed, and the thickness of the cast strip on the exit side of the in-line mill is 1.4 mm.

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

As shown in FIG. 7, the example of the present invention was constituted by a first cooling drum and a second cooling drum that constitute a pair of cooling drums. In addition, the polynomial which comprises 1st curve shape C21 and 2nd curve shape C22 shown in FIG. 7 is taken as the 3rd order polynomial shown in FIG. 3B, for example. The first edge suppression shape E21 and the second edge suppression shape E22 are connected to a tangent in the vicinity of the maximum value of the cubic polynomial shown in FIG. 3B, and the diameter increases as the distance from the first convex curve shape C111 (C122) increases. 20 mR (curvature radius of 20 m).
The first cooling drum is connected to the first convex curve shape in which the diameter of the first cooling drum is reduced from one side of the axis to the other side and the tangent to the axis gradually increases, and the first cooling drum is connected to the first convex curve shape toward 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 being reduced in diameter is formed on the outer peripheral surface. And the 1st edge suppression shape was formed in the one side of the 1st curve shape.
In addition, the second cooling drum is connected to the second concave curve shape in which the diameter of the tangent to the axis gradually increases while being increased in diameter from one side of the axis to the other side, and connected to the second concave curve shape on the other side. A second profile including a second curved line shape having a second convex curved line shape that gradually decreases in diameter and gradually decreases in inclination of the tangent to the axis is formed on the outer peripheral surface. And the 2nd edge suppression shape was formed in the other end side of the 2nd curve shape.
The pair of cooling drums are movable in the axial direction. And, the plate profile change of the thin cast strip after the start of casting obtained by experiment in advance is formulated in correspondence with the time after the start of casting, and the relative position in the axial direction of the pair of cooling drums is controlled based on the formula, The casting 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 after 30 seconds from the start of casting, and an off gauge of about 40 m was generated when the flying touch was started 30 seconds after the start of casting.

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

  From the above, according to the present invention, it was confirmed that the manufacturing cost can be realized by reducing the off-gauge of the casting strip by advancing the timing of the flying touch in the twin-drum type thin cast strip continuous casting equipment.

  According to the twin drum type thin cast slab continuous casting apparatus and the thin cast slab manufacturing method according to the present invention, by reducing the time to the flying touch, the occurrence of off-gauge is suppressed and the yield of the thin cast slab is improved. It can be used industrially.

L One side R The other side S Cast strip (thin wall cast)
T Tundish 10 Twin Drum Type Casting Strip Continuous Casting Equipment (Double Drum Type Thin Wall Casting Equipment)
R10, R20 Pair of cooling drums R11, R21 First cooling roll R12, R22 Second cooling roll PR11, PR21 First profile C11, C21 First curve shape E21 First edge suppression shape PR12, PR22 Second profile C111, C211 1 convex curve shape C112, C212 1st concave curve shape C12, C22 2nd curved shape C121, C221 2nd concave curve shape C122, C222 2nd convex curve shape E22 2nd edge suppression shape 11 dummy sheet 12 protrusion 13 dummy bar 15 Molten metal reservoir 20 Antioxidation device 30 Cooling device 40 First pinch rolls 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 reduction device (reduction means)
50 In-line mills 51A, 51B Work rolls 52A, 52B Intermediate rolls 53A, 53B Backup roll 54 In-line mill control device 541 Hydraulic pressure reduction cylinder 542 Mill hydraulic pressure reduction device 543 Roll rotation speed setting means 544 Roll bending force setting means 545 Roll cross angle setting means 55 Plate thickness gauge 60 Second pinch roll 81 Feed roll 82, 83 Tension roll 84 Deflector roll 70 Winding device

Claims (10)

The molten metal is poured into a molten metal reservoir formed by a pair of cooling drums and side weirs that are rotatable about axes arranged in parallel to each other, and the circumferential surfaces facing each other are faced downward. A twin-drum type thin-walled slab continuous casting apparatus for producing a thin-walled slab 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 includes:
A first convex curve shape in which the diameter of the tangent to the axis gradually decreases while decreasing in diameter from one side of the axis toward the other side, and connected to the first convex curve shape and contracted toward the other side. A first cooling drum in which a first profile including a first curved shape having a first concave curved shape having a gradually decreasing slope of a tangent to the axis while being diametered,
A second concave curve shape in which the diameter of the tangential line with respect to the axis gradually increases while increasing in diameter from one side of the axis toward the other side, and connected to the second concave curve shape and expanded toward the other side. A second cooling drum in which a second profile including a second curved shape having a second curved shape having a gradually decreasing slope of a tangent to the axis while being diameter is formed on the outer peripheral surface;
With
The twin-drum type thin cast slab continuous casting apparatus, wherein the first cooling drum and the second cooling drum are configured to be relatively movable along the axis. The twin-drum type thin-walled slab continuous casting apparatus according to claim 1,
At least one of the first curved line shape and the second curved line shape is defined by a polynomial expression. The twin-drum type thin-walled slab continuous casting apparatus according to claim 1,
At least one of the first curved shape and the second curved shape is defined by a polynomial having a cubic or higher order. It is a twin drum type thin-walled slab continuous casting apparatus according to any one of claims 1 to 3,
Connected to the one side of the first curved shape and expanded in diameter toward the one side, and connected to the other side of the second curved shape and toward the other side Therefore, the twin-drum type thin cast slab continuous casting apparatus is provided with at least one of the expanded second edge suppression shapes. A twin-drum type thin-walled slab continuous casting apparatus according to any one of claims 1 to 4,
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 with the elapsed time after the start of casting and the plate profile of the thin cast slab. A twin-drum type thin-walled slab continuous casting machine. A first convex curve shape in which the diameter of the tangential line with respect to the axis gradually increases while being reduced in diameter as it goes from one side of the axis to the other side, and the diameter is reduced as it is connected to the first convex curve shape and toward the other side. A first cooling drum having a first profile including a first curved shape having a first concave curved shape that gradually decreases a slope of a tangent to the axis,
A second concave curve shape in which the diameter of the tangential line with respect to the axis gradually increases as the diameter increases from one side to the other side of the axis, and the diameter increases as the second concave curve shape is connected to the second concave curve. A second cooling drum in which a second profile including a second curved shape having a tangential slope with respect to the axis gradually decreases, and a second profile including the second curved shape,
A pair of cooling drums with
The molten metal is poured into a molten metal storage portion formed by side weirs 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 form the molten metal. The molten metal injected into the reservoir is solidified and grown on the peripheral surfaces of the pair of cooling drums, and the thin slab is 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 characterized by comprising: It is a manufacturing method of the thin walled slab of Claim 6,
A method for producing a thin cast slab, wherein a pair of cooling drums defined by a polynomial is used for at least one of the first curved shape and the second curved shape. It is a manufacturing method of the thin walled slab of Claim 6,
A method for producing a thin-walled slab, wherein a pair of cooling drums defined by a third or higher order polynomial is used for at least one of the first curved shape and the second curved shape. A method for producing a thin cast slab according to any one of claims 6 to 8,
Connected to the one side of the first curved shape and expanded in diameter toward the one side, and connected to the other side of the second curved shape and toward the other side Therefore, a method for producing a thin cast slab comprising using a pair of cooling drums provided with at least one of the expanded second edge suppression shapes. A method for producing a thin cast slab according to any one of claims 6 to 9,
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 with the elapsed time after the start of casting and the plate profile of the thin cast slab. A method for producing a thin cast slab characterized by

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