JP6620657B2 - Casting strip manufacturing equipment and casting strip manufacturing method - Google Patents

Description

  The present invention relates to a casting strip manufacturing facility including a twin-drum type continuous casting apparatus and an in-line mill, and a casting strip manufacturing method using the casting strip manufacturing facility.

  When manufacturing a casting strip, for example, as shown in Patent Document 1, a pair of continuous casting cooling drums (hereinafter referred to as cooling drums) are arranged in parallel, and the opposing circumferential surfaces are rotated from above to below, respectively. A twin-drum type continuous casting apparatus for continuously casting a casting strip by injecting a molten metal into a hot water reservoir formed by the peripheral surfaces of these cooling drums, cooling and solidifying the molten metal on the peripheral surface of the cooling drum, and A casting strip manufacturing facility including a pinch roll, an in-line mill, and a winding device is used.

As described in Patent Document 1, the twin-drum type continuous casting apparatus solidifies and grows the molten metal poured into the hot water pool portion on the peripheral surface of the rotating cooling drum, and sends the molten metal downward as a casting strip.
And the casting strip sent out from the cooling drum is sent out to a horizontal direction with a pinch roll, and is adjusted to desired plate | board thickness with 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.

In the twin drum type continuous casting apparatus, a dummy sheet is connected to the tip of the casting strip, and the casting strip is pulled out to start casting.
The dummy bar that leads the dummy sheet is formed to be considerably thicker than the cast strip, and a projection 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.
And rolling by an in-line mill is started after the above-mentioned projection part passes an in-line mill.

  In the twin-drum type continuous casting apparatus, the cooling drum is generally at a low temperature before the start of casting. When casting is started, the cooling drum is heated by contact with a high-temperature 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, and the temperature of the cooling drum during steady casting is called steady temperature.

  The profile of the cooling drum changes (thermally expands) with the lapse of time from the start of casting to the time of steady casting. Therefore, the initial profile of the cooling drum has a smaller drum diameter at the center of the cooling drum than at the end of the cooling drum so that the plate profile (plate crown) of the cast strip during steady casting becomes a desired plate profile. It is set to a concave crown. In the cast strip, the difference between the plate thickness at the center of the width and the plate thickness at the crown definition point provided at a predetermined distance from the width edge is called the plate crown, and the plate thickness distribution in the width direction is called the plate profile. It is out. Similarly, in the cooling drum, the difference between the drum diameter at the center of the width and the drum diameter at the crown definition point provided at a predetermined distance from the width end is referred to as a drum crown. Drum crowns may be used for both radial and diameter differences, and are defined as drum crowns per radius and drum crowns per diameter, respectively. The drum diameter distribution or the drum diameter difference distribution in the width direction is called a drum profile.

  As described above, the cooling drum is thermally affected by the start of casting, and as a result, thermally expands. For this reason, the outer peripheral surface (drum profile) of the initial cooling drum is generally processed into a concave shape. Therefore, the plate profile of the cast strip immediately after the start of casting has a distribution such that the plate thickness at the center of the plate is thick and the plate thickness at the plate end is thin, and this plate thickness deviation decreases as the casting time elapses. As a result, the plate profile of the cast strip during steady casting becomes closer to a flat plate surface as the difference between the plate thickness at the center of the plate and the plate thickness at the plate end decreases. The specific crown amount of the casting strip at the time of the steady casting is set so as to satisfy the customer's needs and requirements in the case of the thickness of the final product.

In a casting strip manufacturing facility equipped with such a twin-drum type continuous casting apparatus, there are the following problems when the casting strip is rolled by an in-line mill.
In the in-line mill, since the temperature of the casting strip on the inlet side of the in-line mill is relatively high, some metal flow in the width direction of the plate occurs during rolling, and a slight adjustment of the plate crown is possible. There is no crown control capability to cope with plate profile changes in the cast strip due to thermal expansion of the cooling drum. At this time, if the rolling is intentionally performed, the center portion of the cast strip is extended more than the end portion of the width of the cast strip, resulting in an extremely middle stretch shape, which may cause the cast strip to break.

For this reason, casting is started, and after the tip of the casting strip at the time of steady casting passes through the inline mill, the roll gap is tightened while the roll of the inline mill is rotated, and rolling is started. This rolling method is called flying touch.
Therefore, the casting strip before the steady casting state until the flying touch is out of the plate thickness, that is, off-gauge, and the portion is cut and scrapped in the subsequent process, resulting in a problem that manufacturing efficiency and yield are lowered as a result. there were.
These problems are caused by the change in the plate profile of the cast strip due to the thermal effect at the start of casting of the cooling drum in the twin drum continuous casting facility. Therefore, in order to improve the production efficiency and the yield, it is required to make the plate profile of the cast strip at the start of casting ready for flying touch as soon as possible.

As a method for solving the above problem, it is conceivable to heat the cooling drum in advance to bring it close to the state during steady casting.
Although a specific heating method is not a cooling drum, for example, Patent Document 2 discloses a method of heating a roll using a high-frequency induction heating device as external heating.
Patent Document 3 discloses a method of heating a roll (pinch roll) using a burner as external heating.

In addition, a technique for adjusting the plate profile by controlling the crown shape of the cooling drum has been proposed.
For example, Patent Document 4 discloses a technique in which a sleeve having a concave crown is fitted in a roll for continuously casting a metal plate, and the sleeve is expanded by cooling water pressure supplied into the roll shaft.
Patent Document 5 discloses a technique in which, in a twin-roll continuous casting apparatus, pressure control is performed from the inside of a water-cooled drum using cooling water, and the outer peripheral surface of the water-cooled drum is always kept in a right cylindrical shape during operation. Yes.
Further, in Patent Document 6, in a twin-roll type continuous casting apparatus, a two-layer sleeve of an inner sleeve and an outer sleeve is mounted on the outer periphery of the roll body, and a cooling water flow path is provided between the inner sleeve and the outer sleeve. Discloses a technique for providing a pressure chamber for shape control between the roll body and the roll body.
Further, in Patent Document 7, the pressure fluid grooves are provided at at least three locations, that is, the central portion and both edge portions, and supply of the pressure fluid to these pressure fluid grooves is individually performed at least at the central portion and both edge portions. The technology of a cooling roll provided with a supply system is disclosed.

JP 2000-343103 A JP 2000-225406 A JP-A 64-077866 Japanese Unexamined Patent Publication No. 60-033857 JP-A-61-038745 Japanese Patent Publication No. 07-121440 JP 59-163057 A

  However, in the techniques disclosed in Patent Documents 2 and 3, it is difficult to uniformly heat the cooling drum in the width direction by an external heating device. In the twin roll type continuous casting apparatus, a dummy sheet is used at the start of casting, and the cooling drum is stopped when the dummy sheet is set. Therefore, even if the cooling drum is heated all around by the external heating device in advance, the temperature drop in this part proceeds due to the effect of heat removal from the part in contact with the dummy sheet, and the cooling drum is heated in the circumferential direction. The amount of expansion will be different. For this reason, the plate profile of the cast strip fluctuates with the drum circumferential length pitch of the cooling drum, and the above-mentioned timing of starting the flying touch could not be advanced.

Further, at the start of casting, the profile (crown shape) of the cooling drum changes suddenly, but the change over time in the width direction of the profile (crown shape) of this cooling drum takes the form of a high-order function.
However, the techniques disclosed in Patent Documents 4 to 6 can change the profile of the cooling drum only by a quadratic function. For this reason, after the amount of change in the profile of the cooling drum has settled to a certain level, there is a problem that a flying touch must be performed, the off gauge becomes long, and the yield deteriorates.

In the technique described in Patent Document 7, two or more fluid supply systems are provided in one roll, and the mechanism becomes complicated. In addition, the shape control procedure is complicated, and there is a problem that the crown shape of the cooling drum cannot be adjusted with high accuracy.
As described above, the conventional technique has a problem that although the equipment cost is increased, the effect of reducing the off-gauge cannot be obtained, or the equipment mechanism becomes complicated and the equipment cost is very high.

  The present invention adjusts the plate profile of the cast strip produced in the twin-drum type continuous casting machine, thereby enabling faster flying touch by the in-line mill, resulting in reduced plate breakage and off-gauge and improved yield. It is an object of the present invention to provide a cast strip manufacturing facility capable of reducing the manufacturing cost, and a cast strip manufacturing method using the cast strip manufacturing facility.

  In order to solve the above-mentioned problems, the present inventors investigated the change in the plate profile of the cast strip when the concave drum is attached to the cooling drum so as to obtain a desired plate profile during steady casting as a conventional technique. At this time, no reduction in an in-line mill was performed. FIG. 11 shows a conceptual diagram of the plate profile of the cast strip from the start of casting to the time of steady casting.

  In FIG. 11, the state 1 is a profile of the cooling drum immediately after the start of casting and a plate profile of the casting strip S. The profile of the cooling drum is such that the outer peripheral surface of the cooling drum is directed toward the center in the drum width direction in the initial state. It has a large concave shape as a whole, curved to be convex. For this reason, the plate profile of the cast strip S has a large convex shape as a whole with the plate surface curved so that the plate thickness increases toward the center in the plate width direction.

  State 2 is the profile of the cooling drum and the plate profile of the casting strip S after a while from the start of casting, and the cooling drum expands due to the heat effect from the molten metal. In comparison, the outer peripheral surface of the cooling drum has a concave shape with a gentle curve. Therefore, the plate profile of the cast strip S is a convex shape with a gentle curve on the plate surface as compared with the state 1 described above.

  State 3 is the profile of the cooling drum and the plate profile of the cast strip S when further time has passed from the state 2 state, and the profile of the cooling drum expands further than the state 2 due to the thermal effect from the molten metal, Compared to state 2, the outer peripheral surface of the cooling drum has a slightly concave shape with a gentler curvature. Therefore, the plate profile of the cast strip S has a slightly convex shape with a more gentle curve on the plate surface than in the state 2 described above.

  The state 4 is a profile of the cooling drum and the plate profile of the casting strip S when the steady casting state is reached after a further time from the state 3, and the profile of the cooling drum is more than the state 3 due to the heat effect from the molten metal. Further expansion, resulting in a generally rectangular shape (or a slightly concave shape with a more gradual curve of the outer peripheral surface of the cooling drum than in state 3), and therefore the plate profile of the cast strip S is also substantially rectangular (or Compared with state 3, the surface of the plate has a slightly convex curve with a gentler curvature.

  The change from state 1 to state 4 depends on the type of molten metal (melting temperature) and the thickness of the casting strip S. For example, in this example, state 2 is 18 seconds after the start of casting, and state 3 is After 28 seconds from the start of casting, state 4 is 32 seconds after the start of casting.

Furthermore, the characteristic of the profile change of the cooling drum over the states 1-4 is shown below.
Change to state 1-2: The whole thermally expands from the width center to the width end. When expressed in function form, the profile change amount of the cooling drum in the states 1 and 2 is a quadratic function.
Change from state 2 to state 3: Thermal expansion is performed from the center of the width to the end of the width, but the relative change of the profile at the center of the width is small and the relative change of the profile at the end of the width is large. . When expressed in function form, the profile change amount of the cooling drums in the states 2 to 3 is a high-order function.
Change to state 3-4: It is almost the same as the change of state 2-3, and the whole thermally expands from the width center to the width end, but the relative change of the profile at the width center is small, the width end There is a large relative change in profile. When expressed in function form, the amount of profile change of the cooling drum in states 3 to 4 is a high-order function. However, the absolute quantity is small compared with the change of the states 2-3.
State 4: A steady state is reached, the profile change amount of the cooling drum is small, and the profile of the cooling drum is substantially constant.

At this time, flying touch was started, and an in-line mill was used to examine when to perform rolling with a rolling rate of 30%. The time from the start of the flying touch to the completion of the reduction setting is about 1 second.
First, when the flying touch was made in the state 2 (within 18 seconds from the start of casting), the plate shape was good immediately after rolling, but immediately after that, in the in-line mill, there were abnormal ears at both ends in the width direction of the casting strip. A wave occurred and the cast strip broke.
When the flying touch was made after state 3 (after 28 seconds from the start of casting), the cast strip was not broken, and a thin and thin cast strip with a good plate shape could be produced. In this case, however, the cooling drum acceleration rate is 150 m / min. Since / 30 seconds, an off gauge of about 40 m was generated.

Thus, in order to suppress the occurrence of off-gauge parts as much as possible by starting the predetermined rolling on the casting strip as early as possible, the plate profile of the casting strip is adjusted due to the change in the cooling drum profile over time. Thus, it is necessary to make the flying touch on the cast strip in the in-line mill possible as soon as possible.
As a result of the study by the present inventors, the cooling drum profile was changed over time by assuming that the cooling drum had a concave crown shape in which the diameter of the central portion in the drum width direction was smaller than the diameters at both ends in the drum width direction in the initial state. In addition, if it is possible to change the shape of the higher-order function to the shape of the high-order function, the knowledge that the plate profile of the cast strip formed in the cooling drum can be adjusted to a shape that can be quickly flying-touched in an in-line mill has been obtained. The present invention has been conceived.

  The present invention has been made based on the above-described knowledge, and the casting strip manufacturing facility according to the present invention is a twin-drum type continuous casting in which a molten metal is solidified by a pair of rotating cooling drums to manufacture a casting strip. In a cast strip manufacturing facility comprising an apparatus and an in-line mill for rolling the cast strip to a predetermined thickness, the pair of cooling drums supply a pressure medium to a pressurizing chamber disposed therein, and It is a variable crown roll in which the crown shape of the cooling drum is controlled by discharging, and the concave portion in which the diameter of the central portion in the drum width direction is smaller than the diameter of both end portions in the drum width direction without pressurizing the pressurizing chamber. A crown shape is formed, and at least the diameter of the central portion in the drum width direction can be changed by pressurizing the pressurizing chamber. Drum width direction length L1 of the pressurizing chamber of the cooling drum has a feature that it is shorter than the drum width direction length L2 of the pressure chamber of the other cooling drum.

According to the casting strip manufacturing facility of this configuration, the pair of cooling drums includes a variable crown roll in which a crown amount of the cooling drum is controlled by supply and discharge of a pressure medium to and from a pressurizing chamber disposed therein. Thus, at least the diameter of the central portion in the drum width direction can be changed by pressurizing the pressurizing chamber. Furthermore, a drum width direction length L1 of the pressure chamber of one cooling drum of the pair of cooling drums is shorter than a drum width direction length L2 of the pressure chamber of the other cooling drum. For this reason, the crown amount at the central portion in the drum width direction is controlled by the pressurizing chamber of one cooling drum and the pressurizing chamber of the other cooling drum, and the both ends of the drum width direction are controlled by the pressurizing chamber of the other wide cooling drum. By controlling the crown amount, it is possible to accurately control the crown shape even when the cooling drum has a higher-order shape change due to thermal expansion at the start of casting. It is possible to make the shape capable of flying touch.

Here, in the cast strip manufacturing facility of the present invention, the drum width direction length L1 of the pressure chamber of the one cooling drum, and the drum width direction length L2 of the pressure chamber of the other cooling drum, The ratio L1 / L2 is preferably in the range of 0.6 ≦ L1 / L2 ≦ 0.9.
In this case, the crown shape of the cooling drum can be more accurately controlled in the entire drum width direction with respect to a higher-order shape change of the cooling drum due to thermal expansion at the start of casting.

  The casting strip manufacturing method of the present invention is a casting strip manufacturing method using the above-described casting strip manufacturing equipment, and the cooling drum is subjected to the above-mentioned process in accordance with the change in crown shape due to the thermal expansion of the cooling drum. The pressure medium is supplied to and discharged from the pressure chamber, the crown shape of the cooling drum is controlled, and the plate profile of the casting strip on the inline mill entry side is adjusted.

  According to the casting strip manufacturing method of this configuration, the cooling medium is supplied to and discharged from the pressurizing chamber in each cooling drum in accordance with the change in crown shape due to the thermal expansion of the cooling drum, and the cooling Since the crown shape of the drum is controlled, the plate profile of the casting strip on the entry side of the in-line mill can be made into a shape that allows early flying touch. Therefore, it is possible to reduce plate breakage and off-gauge, and to greatly improve the production efficiency and yield of the cast strip.

Here, in the method for producing a cast strip of the present invention, the relationship between the time from the start of casting and the change over time of the plate profile of the cast strip on the inline mill entry side is obtained in advance, and according to this relationship, A configuration for controlling the crown shape of the cooling drum by adjusting the amount of pressure of the pressure medium by supplying and discharging the pressure medium to and from the pressurizing chamber in each cooling drum so as to have a preset plate profile It is good.
In this case, the relationship between the time from the start of casting and the change over time of the plate profile of the cast strip introduced into the in-line mill is obtained in advance, and the crown shape of the cooling drum is controlled according to this relationship. The plate profile of the casting strip on the entry side of the in-line mill can be easily shaped so that it can be quickly touched by flying.

In the cast strip manufacturing method of the present invention, the plate profile of the cast strip produced from the cooling drum is measured, and the additional processing is performed in each cooling drum according to the measured plate profile of the cast strip. The pressure medium may be supplied to and discharged from the pressure chamber to adjust the pressure amount of the pressure medium, and the crown shape of the cooling drum may be controlled.
In this case, the plate profile of the casting strip produced from the cooling drum is measured, and the crown shape of the cooling drum is controlled according to the measurement result, so that the plate profile of the casting strip can be adjusted with high accuracy, and the inline The plate profile of the casting strip on the entry side of the mill can be made into a shape that allows early flying touch.

Further, in the casting strip manufacturing method of the present invention, the profile of the cooling drum is measured, and the pressure medium is supplied to the pressurizing chamber in each cooling drum in accordance with the measured profile of the cooling drum. In addition, the crown shape of the cooling drum may be controlled by adjusting the pressure amount of the pressure medium by discharging.
In this case, since the profile of the cooling drum is measured and the crown shape of the cooling drum is controlled according to the measurement result, the plate profile of the casting strip can be adjusted with high accuracy, and the casting strip plate on the inline mill entry side can be adjusted. The profile can be made into a shape that enables early flying touch.

  As described above, according to the present invention, by adjusting the plate profile of the cast strip produced in the twin drum type continuous casting apparatus, an in-line mill enables faster flying touch, and as a result, whether the plate breaks or off-gauge. Thus, the yield can be improved and the manufacturing cost can be reduced.

It is explanatory drawing which shows schematic structure of the casting strip manufacturing equipment which is embodiment of this invention. It is explanatory drawing which shows the twin drum type continuous casting apparatus, pinch roll, and in-line mill with which the casting strip manufacturing equipment which is embodiment of this invention was equipped. It is a schematic explanatory drawing of the cooling drum which concerns on embodiment of this invention. It is a conceptual diagram explaining the outline | summary at the time of the casting start at the time of manufacturing a casting strip with the twin drum type continuous casting apparatus which concerns on embodiment of this invention. In embodiment of this invention, it is a schematic explanatory drawing which shows the procedure of the profile control of the cooling drum at the time of a casting start. It is a graph which shows the result of calculating the thermal expansion amount (thermal crown) of a cooling drum, and the crown control range in the embodiment of the present invention. It is explanatory drawing in the case of measuring the plate profile of the casting strip produced from a cooling drum. It is a flowchart in the case of measuring the plate profile of the casting strip produced from a cooling drum, and controlling the crown shape of a cooling drum. It is explanatory drawing in the case of measuring the profile of a cooling drum. It is a flowchart in the case of measuring the profile of a cooling drum and controlling the crown shape of a cooling drum. 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 casting strip at the time of manufacturing a casting strip by the conventional twin drum type continuous casting apparatus.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating a schematic configuration of a casting strip manufacturing facility according to the present embodiment, and FIG. 2 is a schematic configuration diagram illustrating an example of a twin drum type continuous casting apparatus, a first pinch roll, and an inline mill. is there. FIG. 3 is a diagram illustrating a schematic configuration of the cooling drum according to the present embodiment.

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

Further, a feed roll 81 is disposed between the twin drum type continuous casting apparatus 10 and the first pinch roll 40.
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 continuous casting apparatus 10 includes, for example, a pair of cooling drums 100 and side weirs (not shown) arranged on both sides in the width direction of the pair of cooling drums 100. The pair of cooling drums 100 and the side weirs constitute the molten metal reservoir 15.

The pair of cooling drums 100 includes a first cooling drum 100A and a second cooling drum 100B. The first cooling drum 100A and the second cooling drum 100B correspond to the plate thickness (internal quality) of the cast strip S to be manufactured. It is possible to adjust the interval.
In this embodiment, the first cooling drum 100A and the second cooling drum 100B 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 100 are not limited thereto.

Here, the structure of the pair of cooling drums 100 (first cooling drum 100A and second cooling drum 100B) in the embodiment of the invention is shown in FIG.
As shown in FIG. 3, in the first cooling drum 100 </ b> A and the second cooling drum 100 </ b> B, an inner layer sleeve 102 and an outer layer sleeve 103 are mounted on the outer periphery of the drum body 101. A cooling medium flow path 104 through which a cooling medium (for example, water) flows is provided between the outer layer sleeve 103 and the inner layer sleeve 102, and a pressure medium (for example, oil) is supplied between the inner layer sleeve 102 and the drum body 101. Alternatively, a pressurizing chamber 105 to be discharged is provided. In addition, a cooling medium supply path 106 that supplies a cooling medium to the cooling medium flow path 104 and a pressure medium supply path 107 that supplies and discharges the pressure medium to the pressurizing chamber 105 are provided inside the drum body 101. ing.

  The drum width direction length L1 of the pressurizing chamber 105A of the first cooling drum 100A is shorter than the drum width direction length L2 of the pressurization chamber 105B of the second cooling drum 100B. The pressurizing chamber 105B of the second cooling drum 100B is provided over substantially the entire width in the drum width direction, the pressurizing chamber 105A of the first cooling drum 100A is located at the center in the drum width direction, and the second cooling drum 100B The pressure chamber 105B is shorter than the length L2 in the drum width direction. Therefore, the first cooling drum 100A and the second cooling drum 100B have different ranges in which the profile of the cooling drum 100 is controlled.

Although not shown, the cooling medium supply path 106 and the pressure medium supply path 107 are connected to the cooling medium supply pipe and the pressure medium supply pipe via a rotary joint, respectively.
In addition, this invention is not limited to what was shown to the said embodiment, Although the cooling system has shown internal cooling, you may employ | adopt other cooling systems. For example, the cooling medium (cooling water) may be sprayed from the outside, or the cooling drum may be hollow and the cooling medium (cooling water) may be sprayed into the hollow portion to cool.

  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 material of the cast strip S to be cast.

On the downstream side of the twin drum type continuous casting apparatus 10, the feed roll 81 clamps the cast strip S by a reduction device (not shown), and the loop length of the cast strip S between the pair of cooling drums 100 and the feed roll 81 is set. While measuring, the rotational speed 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 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 in accordance with the material of the casting strip S, the cooling water is ejected from the spray nozzle to the surface (upper and lower surfaces) of the casting strip S. S is cooled.

The first pinch roll 40 is a device that applies a pressing force to the casting strip S and applies a tension on the entry side of the in-line mill 50.
Although not shown, the upper pinch roll R40A and the lower pinch roll R40B have a hollow structure and are cooled by water cooling from the inside.

The in-line mill 50 is a device that rolls the cast strip S to reduce the cast strip S to a desired plate thickness. In this embodiment, the in-line mill 50 is a six-high rolling mill.
As shown in FIGS. 1 and 2, the in-line mill 50 includes work rolls 51A and 51B arranged opposite to each other, intermediate rolls 52A and 52B arranged behind the work rolls 51A and 51B, and intermediate rolls 52A and 52B. Backup rolls 53 </ b> A and 53 </ b> B arranged behind, an in-line mill control device (not shown), and a thickness gauge 55 are provided.

The in-line mill 50 measures the plate thickness of the cast strip S by a plate thickness meter (for example, X-ray plate thickness) 55 disposed downstream, and the plate on which the cast strip S is preset based on the measurement result. The roll gap is adjusted so as to be formed thick.
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, the manufacturing method of the casting strip by the casting strip manufacturing equipment 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 continuous casting apparatus 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 100, 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 100 to cast the casting strip S.
When casting is started in the twin-drum type continuous casting apparatus 10, for example, as shown in FIG. 4, 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 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 100 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 100 is subjected to an antioxidant treatment in the antioxidant device 20 as necessary.
(5) Next, the casting strip S is conveyed downstream by the feed roll 81 while keeping the loop length of the cast strip S between the cooling drum 100 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 in-line mill 50 starts the flying touch at a preset timing at 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 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 tension between the inline mill 50 and the second pinch roll 60 is generated in the casting strip S by the second pinch roll 60.
(11) The winding device 70 winds the cast strip S that has been sent.

Here, in the present embodiment, the crown shape of the pair of cooling drums 100 (the first cooling drum 100A and the second cooling drum 100B) is controlled at the start of casting, and the plate profile of the produced casting strip S is adjusted. ing.
Specifically, as shown in FIG. 5A, the first cooling drum 100A and the second cooling drum 100B have a crown shape by adjusting the amount of pressure in the pressurizing chambers 105A and 105B with a pressure medium, respectively. The first cooling drum 100A and the second cooling drum 100B have different lengths in the drum width direction of the pressurizing chambers 105A and 105B. As described above, the pressure of the pressure medium in the pressurizing chambers 105A and 105B can be controlled independently.

The state 1 ′ before and after the start of casting will be described with reference to FIG. In FIG. 5B, the broken line indicates the drum crown shape in the initial state, and the solid line indicates the drum crown shape after being controlled by the pressure chamber 105. As shown in FIG. 5B, in the present embodiment, the cooling drum has a concave crown shape in an initial state where the pressure chamber is not pressurized.
In the state 1 ′ before and immediately after the start of casting, the pressure in the pressure chamber 105B of the second cooling drum 100B (wide pressure chamber) is high, and the pressure in the first cooling drum 100A (pressure chamber narrow) is increased. The pressure in the chamber 105A is lowered. Then, as shown in FIG. 5 (b), the first cooling drum 100A has a concave crown with the drum width center portion retracted radially inward, and the second cooling drum 100B has the drum width center portion protruded radially outward. It becomes a convex crown, and the casting strip S between the first cooling drum 100A and the second cooling drum 100B has a constant thickness in the width direction. Since the pressure in the pressurizing chamber 105B of the second cooling drum 100B (the pressurizing chamber narrow width) is not adjusted, the second cooling drum 100B remains in the initial state (broken line).

Next, the state 2 ′ will be described with reference to FIGS. 5C and 5D. 5C and FIG. 5D, the broken line indicates the drum crown shape in the state 1 ′, the drum crown shape after the one-dot chain line is thermally expanded, and the solid line after being controlled by the pressure chamber 105 The drum crown shape is shown.
In the change of the states 1 ′ to 2 ′, the profile of the cooling drum 100 is changed by a quadratic function, and as shown in FIG. 5C, the shape shown by the broken line is changed to the shape shown by the one-dot chain line. To do.
Therefore, the pressure in the pressurizing chamber 105B of the second cooling drum 100B (wide pressurizing chamber) is lowered to reduce the protrusion amount (convex crown) at the center of the drum width of the second cooling drum 100B. As a result, as shown in FIG. 5D, the casting strip S between the first cooling drum 100A and the second cooling drum 100B has a constant thickness in the width direction. In addition, since the pressure of the pressurizing chamber 105B of the second cooling drum 100B (the pressurizing chamber narrow width) is not adjusted, the second cooling drum 100B remains in a drum crown shape (one-dot chain line) after being thermally expanded. .

Next, the state 3 ′ will be described with reference to FIGS. 5 (e) and 5 (f). 5 (e) and 5 (f), the broken line indicates the drum crown shape in the state 2 ′, the drum crown shape after the one-dot chain line is thermally expanded, and the solid line after being controlled by the pressure chamber 105. The drum crown shape is shown.
In the change of the states 2 ′ to 3 ′, the profile of the cooling drum 100 is changed by a high-order function, and as shown in FIG. 5E, the shape shown by the broken line is changed to the shape shown by the one-dot chain line. To do.
Therefore, the pressure in the pressure chamber 105A of the first cooling drum 100A (narrow pressure chamber width) is increased so that the central portion of the drum width of the first cooling drum 100A protrudes outward in the radial direction, and the second cooling is performed. The pressure in the pressurizing chamber 105B of the drum 100B (wide pressurizing chamber) is lowered, and the drum width center portion of the second cooling drum 100B is retracted inward in the radial direction. As a result, as shown in FIG. 5F, the casting strip S between the first cooling drum 100A and the second cooling drum 100B has a constant thickness in the width direction.

Next, the state 4 ′ will be described with reference to FIGS. 5 (g) and 5 (h). 5 (g) and FIG. 5 (h), the broken line indicates the drum crown shape in the state 3 ', the drum crown shape after the one-dot chain line is thermally expanded, and the solid line after being controlled by the pressure chamber 105 The drum crown shape is shown.
In the state 3 ′ to 4 ′, the profile of the cooling drum 100 is changed by a high-order function, and as shown in FIG. 5 (g), the shape shown by the broken line is changed to the shape shown by the one-dot chain line. To do.
Therefore, the pressure of the pressurizing chamber 105A of the first cooling drum 100A (narrow pressurizing chamber width) is increased so that the central portion of the drum width of the first cooling drum 100A further protrudes radially outward, and the second The pressure in the pressurizing chamber 105B of the cooling drum 100B (wide pressurizing chamber) is lowered, and the drum width central portion of the second cooling drum 100B is further retracted radially inward. As a result, as shown in FIG. 5H, the casting strip S between the first cooling drum 100A and the second cooling drum 100B has a constant thickness in the width direction.

  In the state 4 ', a steady state is obtained, and the profile of the cooling drum 100 hardly changes. By maintaining the final pressure control amount at the time of the change of the states 3 'to 4', the plate profile of the cast strip S is maintained in a steady state.

In addition, as the initial profile of the cooling drum 100, the amount of thermal crown of the steady state drum is obtained, and the initial cooling drum is set to the concave profile by the amount of the thermal crown, so that the low crown is changed from the initial state to the steady state. A cast strip S can be produced.
FIG. 6 shows a calculation result example of the thermal expansion amount of the cooling drum in the steady state. The calculation conditions are a drum diameter of 500 mm and a drum body length of 1200 mm. In addition, an approximate curve in the second order is also shown.

  FIG. 6A shows that the thermal expansion amount is a high-order function at the plate width end (drum width end). Further, the dimensionless position in the drum width direction (the drum width end is set to −0.5, +0.5, and the drum width center is set to 0) is near −0.375, which is closer to the width end than the vicinity of +0.375. It can be seen that the deviation from the next curve increases.

  Here, as shown in FIG. 6B, by controlling the pressure in the pressurizing chamber 105A of the first cooling drum 100A and the pressurizing chamber 105B of the second cooling drum 100B, thermal expansion can be performed from a flat drum profile. If the time drum profile can be expressed, it is possible to stably cancel the influence of the thermal expansion amount of the cooling drum 100 (the first cooling drum 100A and the second cooling drum 100B) on the plate profile by pressure control. Become.

  Therefore, the length in the drum width direction of the pressurizing chamber 105A of the first cooling drum 100A is L1, the length in the drum width direction of the pressurizing chamber 105B of the second cooling drum 100B is L2, and the width of each pressurizing chamber 105A, 105B. When the center and the width center of the drum were the same, the ratio of L1 / L2 was appropriately changed to measure the drum profile. As a result, the cooling drum 100 (the first cooling drum 100A and the first cooling drum 100A) is obtained when 0.6 ≦ L1 / L2 ≦ 0.9, and more preferably 0.7 ≦ L1 / L2 ≦ 0.8. It has been found that a high-order function of the thermal expansion amount of the cooling drum 100 (the first cooling drum 100A and the second cooling drum 100B) can be expressed with high accuracy over the entire width direction of the two cooling drums 100B).

  Note that the generation of ear waves can be accurately suppressed by setting the ratio of L1 / L2 to 0.6 or more, and the occurrence of medium elongation can be suppressed accurately by setting L1 / L2 to 0.9 or less. be able to. As described above, by making L1 / L2 within the above-mentioned range, the temporal change of the thermal crown can be controlled within ± 20 μm, and the occurrence of flat shape defects can be sufficiently suppressed in the subsequent rolling process. It becomes.

  Therefore, the ratio L1 / L2 between the length L1 of the pressurizing chamber 105A of the first cooling drum 100A and the length L2 of the pressurizing chamber 105B of the second cooling drum 100B is 0.6 ≦ When L1 / L2 ≦ 0.9, the influence of the drum thermal expansion amount on the plate profile can be canceled more accurately by pressure control. Thereby, it is possible to stably build a plate profile of almost the same casting strip S immediately after the start of casting over a steady state.

  Here, the control of the crown shape in the cooling drum 100 (the first cooling drum 100A and the second cooling drum 100B) is performed by the time from the start of casting in advance and the time profile of the plate profile of the casting strip S introduced into the in-line mill 50. A relationship with the change may be obtained, and the pressure amounts of the pressure chambers 105A and 105B of the first cooling drum 100A and the second cooling drum 100B may be adjusted according to this relationship.

  Further, as shown in FIG. 7, the plate profile of the cast strip S produced from the cooling drum 100 is measured by the fixed plate thickness meter 16 and the scan plate thickness meter 17, and according to the measured plate profile of the cast strip S. Thus, as shown in the flowchart shown in FIG. 8, the pressure amounts of the pressure chambers 105A and 105B of the first cooling drum 100A and the second cooling drum 100B may be controlled.

  Alternatively, as shown in FIG. 9, the profile of the cooling drum 100 (the first cooling drum 100 </ b> A and the second cooling drum 100 </ b> B) is measured by a plurality of laser rangefinders 18 arranged at regular intervals in the width direction of the cooling drum 100. Can be obtained by measurement. Then, according to the profile of the cooling drum 100 (the first cooling drum 100A and the second cooling drum 100B) obtained by the measurement by these laser distance meters, as shown in the flowchart shown in FIG. 10, the first cooling drum The amount of pressure in each of the pressure chambers 105A and 105B of 100A and the second cooling drum 100B may be controlled.

  As described above, according to the present embodiment, the pair of cooling drums 100 can control the crown amount of the cooling drum 100 by supplying and discharging the pressure medium to and from the pressurizing chamber 105 disposed in the first cooling drum 100. The drum width direction length L1 of the pressurizing chamber 105A of the drum 100A is shorter than the drum width direction length L2 of the pressurizing chamber 105B of the second cooling drum 100B. Therefore, by supplying and discharging the pressure medium to and from the pressurizing chambers 105A and 105B of the first cooling drum 100A and the second cooling drum 100B, a higher-order shape change of the cooling drum 100 due to thermal expansion at the start of casting. In contrast, the crown shape can be controlled with high accuracy, and the plate profile of the casting strip S on the in-line mill 50 entry side can be made into a shape that allows early flying touch. Therefore, plate breakage and off-gauge can be reduced, and the production efficiency and yield of the cast strip S can be greatly improved.

  In this embodiment, the ratio L1 / L2 between the drum width direction length L1 of the pressurizing chamber 105A of the first cooling drum 100A and the drum width direction length L2 of the pressurization chamber 105B of the second cooling drum 100B. Is within the range of 0.6 ≦ L1 / L2 ≦ 0.9, and more preferably within the range of 0.7 ≦ L1 / L2 ≦ 0.8, so cooling by thermal expansion at the start of casting The crown shape of the cooling drum 100 can be more accurately and stably controlled with respect to the higher-order shape change of the drum 100 in the entire drum width direction.

  Here, in this embodiment, the relationship between the time from the start of casting and the temporal change of the plate profile of the casting strip S introduced into the in-line mill 50 is obtained in advance, and the first cooling drum 100A is determined according to this relationship. When the pressure amount in each of the pressurizing chambers 105A and 105B of the second cooling drum 100B is adjusted and the crown shape of the cooling drum 100 is controlled, the casting on the entry side of the inline mill 50 is relatively easy. The plate profile of the strip S can be made into a shape that allows early flying touch.

  In the present embodiment, the plate profile of the casting strip S produced from the cooling drum 100 is measured, and each of the first cooling drum 100A and the second cooling drum 100B is measured according to the measured plate profile of the casting strip S. When the pressure amount in the pressurizing chambers 105A and 105B is adjusted to control the crown shape of the cooling drum 100, the plate profile of the casting strip S can be adjusted with high accuracy, and the casting strip on the inlet side of the in-line mill 50 can be adjusted. The plate profile of S can be made into a shape that allows early flying touch.

  Further, in the present embodiment, the profile of the cooling drum 100 is measured, and the pressures in the pressure chambers 105A and 105B of the first cooling drum 100A and the second cooling drum 100B are measured according to the measured profile of the cooling drum 100. When the amount is adjusted and the crown shape of the cooling drum 100 is controlled, the plate profile of the casting strip S can be adjusted with high accuracy, and the plate profile of the casting strip S on the inline mill 50 entry side can be quickly flying touched. Possible shapes.

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 present embodiment, the dummy sheet is used at the start of casting. However, the present invention is not limited to this, and the present invention may be applied to a twin-drum continuous casting apparatus having another configuration.

Next, experimental results confirming the effects of the present invention will be described.
The equipment used in this experiment is the same as that shown in FIGS. The thickness of the cast strip is 2 mm, and the plate width is 1200 mm. The acceleration rate of the cooling drum from the start of casting is 150 m / min. / 30 seconds, the cooling drum rotation speed in the steady casting state is 159 m / min. It is. At that time, rolling with a reduction rate of 30% is performed in an in-line mill, and the thickness of the in-line mill exit side is 1.4 mm.

(Comparative Example 1)
A comparative example 1 is a case where the cooling drum is provided with a concave crown (100 μm / radius) over a 1200 mm drum length so that the plate crown of the cast strip after casting in a steady casting state is 30 μm. In Comparative Example 1, no pressurizing chamber in the cooling drum is installed.

(Comparative Example 2)
In the steady casting state, the cooling drum is provided with a concave crown (100 μm / radius) over 1200 mm so that the crown of the cast strip after casting is 30 μm, and a pair of cooling drums A method in which the pressure chambers are installed with the same width and the roll crown is controlled by the pressure medium is referred to as Comparative Example 2.

(Invention Examples 1 to 4)
As a cooling drum, a concave crown (100 μm / radius) was given over a drum length of 1200 mm, and a variable crown roll was used in which a pressurizing chamber was installed in a cooling drum of a casting facility and the crown amount was controlled by a pressure medium. Further, the pressure chambers have different widths for each of the pair of drums. Here, when the narrow pressurizing chamber width is L1, the wide pressurizing chamber width is L2, and the center of the width of each pressurizing chamber is equal to the center of the width of the drum, the ratio of L1 / L2 is shown in Table 1. As shown in
Furthermore, an experiment is performed in advance to obtain a relationship between the time from the start of casting and the plate profile change of the cast strip in advance, and the pressure medium of the cooling drum is determined from the plate profile change of the cast strip so as to obtain a preset plate profile. The amount of pressure was controlled.

  In Comparative Examples 1 and 2 and Invention Examples 1 to 4, flying touch was started, and the flying touch start timing at which no plate breakage occurred in an in-line mill was investigated. The results are shown in Table 1.

  In Comparative Example 1, when a flying touch was started in 10 seconds from the start of casting, an extremely medium elongation occurred immediately after the start of the flying touch, and the plate broke. The flying touch start time at which no plate breakage occurred was 28 seconds after the casting start, and when the flying touch start was changed to 28 seconds from the casting start, an off gauge of about 40 m or less was generated. In this case, the plate crown of the cast strip (plate crown on the inline mill entry side, edge 75 mm position) was initially 160 μm and the stationary part was 30 μm.

  In Comparative Example 2, the flying touch was started 10 seconds after the start of casting, and pressure control was also performed so that the plate crown on the inline mill entry side was kept constant. The inline exit side was flat until 18 seconds after the start of casting, but an ear wave was generated around 20 seconds after the start of casting. The rolling was stopped because of an abnormal ear wave. The flying touch start time for suppressing the flat shape defect to the extent that the lower process plate can be passed is 28 seconds after the casting start, and when the flying touch start is 28 seconds from the casting start, an off gauge of about 40 m or less was generated. In this case, the plate crown of the cast strip (plate crown on the in-line mill entry side, edge 75 mm position) was initially 50 μm and the steady portion was 30 μm.

  In Example 1 of the present invention, no problem occurred when the pressure control was performed so that the flying touch was started 12 seconds from the start of casting and the plate crown on the in-line mill entry side was kept constant. When the flying touch start was 12 seconds from the start of casting, an off gauge of about 16 m was generated. In this case, the plate crown of the cast strip (the plate crown on the in-line mill entry side) was initially 36 μm and the stationary part was 30 μm.

  In Example 2 of the present invention, the flying touch was started 8 seconds after the start of casting, and the pressure was controlled so that the plate crown on the entry side of the in-line mill was kept constant, no problem occurred. When the flying touch was started for 8 seconds from the start of casting, an off-gauge of about 10 m was generated. In this case, the plate crown of the cast strip (the plate crown on the inline mill entry side) was 30 μm at the initial steady portion.

  In Example 3 of the present invention, the flying touch was started 10 seconds after the start of casting, and the pressure was controlled so that the plate crown on the in-line mill entry side was kept constant, no problem occurred. When the flying touch was started for 10 seconds from the start of casting, an off gauge of about 13 m was generated. In this case, the plate crown of the cast strip (the plate crown on the inline mill entry side) was initially 35 μm and the steady portion was 30 μm.

  In Example 4 of the present invention, the flying touch was started 10 seconds after the start of casting, and pressure control was also performed so that the plate crown on the inline mill entry side was kept constant. The inline exit side was flat until 18 seconds after the start of casting, but an ear wave was generated from about 24 seconds after the start of casting. Since rolling occurred, rolling was stopped. The initial drum profile and the flying touch start time were adjusted in order to suppress the flat shape defect so that the plate could pass through the lower process. The flying touch start time to suppress the flat shape defect to the extent that the lower process plate can be passed is 20 seconds after the casting start, and when the flying touch start is 20 seconds from the casting start, an off gauge of about 26 m was generated. In this case, the plate crown of the cast strip (the plate crown on the inline mill entry side, the edge 75 mm position) was 42 μm in the initial stage and 30 μm in the stationary part.

In Examples 1 to 4 of the present invention, it was possible to make the timing of the flying touch earlier than those of Comparative Examples 1 and 2, and as a result, off-gauge could be reduced.
From the above, according to the present invention, in the casting strip manufacturing facility equipped with the twin drum type continuous casting apparatus and the in-line mill, it has become clear that the off-gauge can be reduced by reducing the flying touch time, thereby reducing the manufacturing cost. .

S Casting strip 1 Casting strip manufacturing equipment 10 Twin-drum type continuous casting apparatus 50 In-line mill 100 Cooling drum 100A First cooling drum 100B Second cooling drum 105 (105A, 105B) Pressurizing chamber

Claims (6)

In a casting strip manufacturing facility comprising: a twin-drum type continuous casting apparatus that solidifies a molten metal by a pair of rotating cooling drums to manufacture a casting strip; and an in-line mill that rolls the casting strip to a predetermined thickness.
The pair of cooling drums are variable crown rolls in which the crown shape of the cooling drum is controlled by supplying and discharging a pressure medium to and from the pressurizing chamber disposed therein, and the pressurizing chamber is not pressurized. In addition to forming a concave crown shape in which the diameter of the central part in the drum width direction is smaller than the diameters at both ends in the drum width direction, at least the diameter of the central part in the drum width direction can be changed by pressurizing the pressurizing chamber And
A drum width direction length L1 of the pressure chamber of one cooling drum of the pair of cooling drums is shorter than a drum width direction length L2 of the pressure chamber of the other cooling drum. Casting strip manufacturing equipment.   The ratio L1 / L2 of the length L1 of the pressure chamber of the one cooling drum in the drum width direction and the length L2 of the pressure chamber of the other cooling drum in the width direction of the pressure chamber is 0.6 ≦ L1 / 2. The cast strip manufacturing facility according to claim 1, wherein L2 ≦ 0.9. A cast strip manufacturing method using the cast strip manufacturing facility according to claim 1 or 2,
According to the change in the crown shape due to the thermal expansion of the cooling drum, the pressure medium is supplied to and discharged from the pressurizing chamber in each cooling drum, and the crown shape of the cooling drum is controlled.
A method for producing a cast strip, comprising adjusting a plate profile of the cast strip on the inlet side of the in-line mill. Obtain the relationship between the time from the start of casting in advance and the change over time in the plate profile of the casting strip on the entry side of the inline mill,
In accordance with this relationship, the pressure medium is supplied to and discharged from the pressurizing chamber in each cooling drum so as to have a preset plate profile, and the pressure amount of the pressure medium is adjusted. 4. The method for producing a cast strip according to claim 3, wherein the crown shape is controlled.   The plate profile of the cast strip produced from the cooling drum is measured, and the pressure medium is supplied to and discharged from the pressurizing chamber in each cooling drum according to the measured plate profile of the cast strip. 4. The method for producing a cast strip according to claim 3, wherein a pressure amount of the pressure medium is adjusted to control a crown shape of the cooling drum.   Measure the profile of the cooling drum, and adjust the amount of pressure of the pressure medium by supplying and discharging the pressure medium to and from the pressurizing chamber in each cooling drum according to the measured profile of the cooling drum. The method of manufacturing a cast strip according to claim 3, wherein a crown shape of the cooling drum is controlled.

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