JP6631393B2 - Twin-drum continuous casting apparatus and method for manufacturing metal ribbon - Google Patents

Description

  The present invention relates to a twin-drum continuous casting apparatus for producing a metal ribbon by solidifying molten metal by a pair of rotating cooling drums, and a method for producing a metal ribbon using the twin-drum continuous casting apparatus.

  When manufacturing a metal ribbon, for example, as shown in Patent Literature 1, a pair of cooling drums for continuous casting (hereinafter, referred to as cooling drums) are arranged in parallel, and the opposing peripheral surfaces are rotated downward from above. Twin-drum continuous casting in which molten metal is poured into the pool formed by the peripheral surfaces of these cooling drums, and the molten metal is cooled and solidified on the peripheral surface of the cooling drum to continuously cast thin metal ribbons. The device is used. Such a twin-drum continuous casting apparatus is applied to various metals.

  In the twin-drum continuous casting apparatus, the cooling drum is generally at a low temperature before the start of casting. When casting is started, the temperature of the cooling drum rises due to contact with the high-temperature molten metal. The cooling drum is cooled from the inner surface by a cooling medium (for example, cooling water) so as not to reach a certain temperature or higher. The period after the temperature of the cooling drum reaches a constant 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 (expands thermally) with the passage of time from the start of casting to the time of steady casting. Therefore, the initial diameter of the cooling drum is set such that the diameter of the drum at the center of the width of the cooling drum is smaller than the diameter of the drum at both ends of the cooling drum so that the sheet profile (crown) of the metal ribbon at the time of steady casting becomes a desired sheet profile. Is also set to a reduced concave crown. (Hereinafter, the initial diameter distribution of the cooling drum is referred to as an initial crown.)

  As described above, since the concave crown is set in the cooling drum at the start of casting, the plate profile of the metal ribbon immediately after the start of casting has a large plate thickness at the center of the plate and a plate thickness at the plate end. The thickness deviation decreases as the casting time elapses, and the plate profile of the metal strip at the time of steady casting has the plate thickness at the center of the plate and the plate thickness at the end of the plate. The difference becomes smaller, and the plate approaches a flat plate surface. The specific crown of the metal strip at the time of this steady casting is set so as to satisfy customer requirements when the thickness of the final product is reduced.

  Here, as means for controlling the crown of the metal ribbon, for example, in Patent Documents 1 and 2, the rotating shafts of a pair of cooling drums are inclined in directions opposite to each other in a plane parallel to the plate surface of the metal ribbon. A technique has been disclosed in which the distribution of the closest approach distance between a pair of cooling drums in the width direction is quadratic.

When a metal ribbon is manufactured by a twin-drum continuous casting apparatus, a pair of cooling drums are arranged such that their rotation axes are parallel to each other when viewed from the casting direction (a method of drawing the metal ribbon). Inside, the metal ribbon is clamped with a predetermined pressing force while keeping the rotation axis parallel. The reaction force from the metal ribbon changes depending on the solidification state, and may be uneven in the width direction. For this reason, considering the rigidity of the mechanical device, it is difficult to keep the parallelism of the rotation axes of the pair of cooling drums strictly. For this reason, a difference in thickness at both ends, a so-called wedge, may occur in the metal ribbon. Further, when the unevenness in the width direction of the reaction force from the metal ribbon includes the width center portion and both end portions, the crown is also affected.
Such a wedge cannot be controlled by the methods described in Patent Documents 1 and 2.

  Here, in the twin-drum continuous casting apparatus, in order to change the thickness of the metal strip to be cast, and to apply a narrow pressure to the metal ribbon, a pair of cooling drums are provided with a plate of the metal ribbon. A drum opening / closing mechanism that adjusts an interval by moving in a direction perpendicular to the plane is provided. For example, in Patent Document 3, in order to maintain the parallelism of a pair of opposed cooling drums, hydraulic cylinders are provided at both ends in the axial direction of the cooling drum, and the position of these hydraulic cylinders is controlled individually. A structure that always moves the same amount is disclosed.

  In addition, in the twin-drum continuous casting apparatus, the thickness of the metal ribbon locally increases due to a change in the solidification state, particularly immediately after the start of casting. In some cases, a narrow pressure cannot be applied to the ribbon. As a countermeasure against this, Patent Document 4 discloses a method in which an accumulator is provided in a hydraulic circuit and a cooling drum is elastically pressed against a metal ribbon.

JP-A-60-024250 Japanese Patent Publication No. 06-102255 Japanese Patent Publication No. 03-069616 Japanese Patent No. 2957040

By the way, in Patent Document 3, the hydraulic circuit is switched after the solidification state is stabilized, and the position is controlled while maintaining the parallelism of the cooling drum. Therefore, there is a problem that it takes a long time to obtain a metal ribbon having a predetermined shape with stable casting. Further, there is a problem that the hydraulic device becomes complicated.
Further, as in Patent Document 4, in a structure in which hydraulic cylinders are disposed at both ends in the axial direction of a cooling drum and these hydraulic cylinders are individually position-controlled, an accumulator is disposed to provide elasticity. Has a problem that the parallelism of the pair of cooling drums cannot be kept strictly.

  The present invention provides a twin-drum continuous casting apparatus capable of accurately adjusting a crown and a wedge of a metal ribbon and producing a high-quality metal ribbon having a stable thickness distribution in a width direction, and It is another object of the present invention to provide a method for manufacturing a metal ribbon using the twin-drum continuous casting apparatus.

In order to solve the above problems, a twin-drum continuous casting apparatus according to the present invention is a twin-drum continuous casting apparatus that solidifies a molten metal by a pair of rotating cooling drums to produce a metal ribbon, A first moving mechanism for moving at least one of the pair of cooling drums in a direction orthogonal to the plate surface of the metal ribbon; and a direction parallel to the plate surface of the metal ribbon. And a second moving mechanism for moving the cooling drum in a plane parallel to a plate surface of the metal ribbon by tilting a rotation axis of the cooling drum. An intersection angle adjustment mechanism that adjusts an intersection angle of the rotating shaft; an offset mechanism that adjusts an offset amount in a casting direction of the pair of cooling drums while maintaining the intersection angle of the pair of cooling drums; Before It is characterized in that it comprises a and a offset control unit for controlling the offset amount of the pair of cooling drums.
In the present invention, the offset amount means a shift amount of a mutual position in the casting direction of the pair of cooling drums at the center of the width of the pair of cooling drums.

  According to the twin-drum continuous casting device having this configuration, the first moving mechanism that moves at least one of the pair of cooling drums in a direction orthogonal to the plate surface of the metal ribbon, The second moving mechanism for moving the cooling drum in a direction parallel to the plate surface of the metal ribbon is provided independently of each other, so that the opening degree between the pair of cooling drums is adjusted by the first moving mechanism. In addition, the pair of cooling drums can be moved by the second moving mechanism in a direction parallel to the plate surface of the metal ribbon.

  In addition, the rotation axis of the pair of cooling drums is inclined to intersect with each other, so that the distribution in the width direction of the closest approach distance between the pair of cooling drums can be formed into a quadratic curve. Here, in the present invention, the second moving mechanism adjusts the crossing angle of the rotation axes of the pair of cooling drums by inclining the rotation axis of the cooling drum in a plane parallel to the plate surface of the metal ribbon. Therefore, the crown of the metal ribbon can be controlled by adjusting the intersection angle of the rotation shafts of the pair of cooling drums.

When the relative positions in the casting direction of the pair of cooling drums are offset in a state where the rotation axes of the pair of cooling drums are inclined and cross each other, the width direction of the closest approach distance between the pair of cooling drums is reduced. The center of the quadratic curve indicating the distribution moves from the center of the width to the end of the width, and a difference is provided in the closest approach distance between the pair of cooling drums at one end and the other end in the width direction of the cooling drum. Becomes possible. Here, in the present invention, since the second moving mechanism is provided with an offset mechanism for adjusting the offset amount in the casting direction of the pair of cooling drums while maintaining the intersection angle of the pair of cooling drums, By adjusting the thickness, it is possible to adjust the difference in the thickness of both ends of the metal ribbon, that is, the so-called wedge.
The difference in the closest approach distance between the one end side and the other end side in the width direction of the cooling drum caused by the offset changes according to the intersection angle. Therefore, the offset amount of the pair of cooling drums depends on the intersection angle. Is provided, it is possible to accurately control the offset amount according to the wedge of the metal ribbon.
As a result, it is possible to simultaneously and accurately control the crown and the wedge of the metal ribbon.

Here, in the twin-drum continuous casting apparatus of the present invention, in the second moving mechanism, the intersection angle adjusting mechanism and the offset mechanism may be configured by a common mechanism.
In this case, by providing one mechanism as a second moving mechanism for moving the pair of cooling drums in a direction parallel to the plate surface of the metal ribbon, the cross angle adjusting mechanism and the offset mechanism can be configured. In addition, the device configuration is simplified.

Further, in the twin-drum continuous casting apparatus of the present invention, the first moving mechanism is configured to at least maintain the pair of cooling drums in a plane perpendicular to the plate surface of the metal ribbon while maintaining a state in which the pair of cooling drums are parallel to each other. It is preferable to provide a guide portion for moving one cooling drum in a direction orthogonal to the plate surface of the metal ribbon.
In this case, it is possible to control the opening / closing of the cooling drum, the crossing angle and the offset amount while keeping the pair of cooling drums parallel to each other, and to accurately control the thickness of the metal ribbon, the crown and the wedge. It can be carried out.

Further, in the twin-drum continuous casting apparatus according to the present invention, it is preferable that a thickness distribution measuring device that measures a width direction thickness distribution of the metal ribbon is disposed downstream of the pair of cooling drums.
In this case, the width distribution thickness measurement of the metal ribbon is measured by a thickness distribution measuring device, and the crossing angle adjustment mechanism and the offset mechanism can be feedback-controlled using the measured values, and the crown of the metal ribbon and Wedge control can be performed with higher accuracy.

The method for producing a metal ribbon according to the present invention is a method for producing a metal ribbon using the twin-drum continuous casting apparatus described above, wherein a difference in thickness between a width center portion and a width end portion of the metal ribbon is determined. It is characterized in that it is adjusted by the crossing angle adjusting mechanism, and the difference in thickness between both ends of the metal ribbon is adjusted by the offset mechanism.
According to the method for manufacturing a metal ribbon having this configuration, since the above-described twin-drum continuous casting apparatus is used, the difference in the thickness (crown) between the width center portion and the width end of the metal ribbon is determined by the intersection. A high-quality metal ribbon having a stable thickness distribution in the width direction is manufactured by adjusting the angle difference adjusting mechanism and adjusting the difference (wedge) between the thicknesses of both ends of the metal ribbon by the offset mechanism. Becomes possible.

Here, in the manufacturing method of the metal ribbon of the present invention, the thickness distribution measuring device is used to measure the width direction thickness distribution of the metal ribbon using the twin-drum continuous casting apparatus described above, The intersection angle adjusting mechanism and the offset so that the difference in thickness between the width center portion and the width end portion becomes a predetermined target value, and the difference in thickness between both end portions of the metal ribbon becomes small. It is preferable that the mechanism is configured to perform feedback control.
In this case, the thickness distribution measuring device measures the width direction thickness distribution of the metal ribbon, and the crossing angle adjustment mechanism and the offset mechanism are feedback-controlled, so that the control of the crown and the wedge of the metal ribbon can be performed accurately. It is possible to do well.

  As described above, according to the present invention, in the twin-drum continuous casting apparatus, the rotation axis of the cooling drum is inclined in a plane parallel to the plate surface of the metal ribbon, and the intersection angle of the pair of cooling drums is set. By adjusting and adjusting the offset amount in the casting direction of the pair of cooling drums while maintaining the crossing angle of the pair of cooling drums, the crown and wedge of the metal ribbon can be accurately adjusted, and in the width direction. It is possible to manufacture a high-quality metal ribbon having a stable thickness distribution.

It is an explanatory view showing the schematic structure of the twin drum type continuous casting device which is an embodiment of the present invention. It is an explanatory view of a second moving mechanism. It is a perspective view showing the outline of the circumference of the cooling drum in the twin drum type continuous casting device which is an embodiment of the present invention. FIG. 4 is an explanatory top view of the periphery of the cooling drum shown in FIG. FIG. 4 is an explanatory side view of the vicinity of the cooling drum shown in FIG. It is explanatory drawing which shows the closest approach distance between the cooling drums when the rotation axis of a pair of cooling drums crosses. FIG. 7 is a graph showing the distribution of the closest approach distance between the cooling drums in the width direction in FIG. 6. It is explanatory drawing which shows the closest approach distance between cooling drums when the offset amount of the casting direction of a cooling drum is changed, maintaining the crossing angle of a pair of cooling drums. 6 is a graph showing a relationship between an offset amount and a distribution in a width direction of a closest approach distance between cooling drums. 6 is a graph showing a relationship between an offset amount and a distribution in a width direction of an amount of change in a closest approach distance between cooling drums. 9 is a graph showing a relationship between an offset amount when the intersection angle is changed and a width direction distribution of a change amount of a closest approach distance between the cooling drums.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, a twin-drum continuous casting apparatus 10 according to the present embodiment includes a pair of cooling drums (a first cooling drum 100A and a second cooling drum 100B) and a pinch roll 13 that supports a metal ribbon S. And a side weir 15 disposed at the widthwise ends of the pair of cooling drums 100A and 100B, and a molten metal pool 16 defined by the pair of cooling drums 100A and 100B and the side weir 15. A tundish 18 for holding the molten metal 3, and an immersion nozzle 20 for supplying the molten metal 3 from the tundish 18 to the molten metal pool 16.

  In the present embodiment, the pair of cooling drums (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 1200 mm. It is needless to say that the outer diameter and the drum body length (width) of the pair of cooling drums 100 are not limited to these.

Here, the peripheral structure of the pair of cooling drums 100A and 100B in the present embodiment is shown in FIGS.
In the twin-drum continuous casting apparatus 10 according to the present embodiment, at least one of the pair of cooling drums 100A and 100B (in the present embodiment, as shown in FIGS. 100A) in a direction (horizontal direction in this embodiment) perpendicular to the plate surface of the metal ribbon S, and a direction in which the pair of cooling drums 100A and 100B are parallel to the plate surface of the metal ribbon S. (In the present embodiment, in the vertical direction).

Here, in the twin-drum continuous casting apparatus 10 according to the present embodiment, the first cooling drum 100 </ b> A and the second cooling drum 100 </ b> B have both ends of their respective rotating shafts supported by the chock 103 as shown in FIG. 2. The chocks 103 are provided in the tilting frame 121.
The tilting frame 121 is configured to vertically move the chocks 103 provided at both ends of the rotation shafts of the first cooling drum 100A and the second cooling drum 100B.

Here, the mechanism for moving the chock 103 up and down in the tilting frame 121 is not particularly limited. For example, a method in which a hydraulic ram 122 is installed below the chock 103 and pressed by a spring 123 from above may be used. If the spring force is sufficient, the spring 123 may be installed at the lower part and the hydraulic ram 122 may be installed at the upper part, and it may be changed between one side and the other end of the cooling drums 100A and 100B.
In the present embodiment, the hydraulic ram 122 is provided below the chock 103, and the spring 123 is provided above the chock 103.

By using the tilting frame 121, the rotation axes of the first cooling drum 100A and the second cooling drum 100B are inclined in a plane parallel to the plate surface of the metal ribbon S, and the rotation axes of the pair of cooling drums 100A and 100B are rotated. Can be adjusted.
Further, it is possible to adjust the offset amount in the casting direction (vertical direction) of the pair of cooling drums 100A and 100B while maintaining the intersection angle 2θ between the rotation axes of the pair of cooling drums 100.

That is, in the present embodiment, the tilting frame 121 constitutes a second moving mechanism that moves the pair of cooling drums 100A and 100B in a direction parallel to the plate surface of the metal ribbon S (vertical direction in the present embodiment). ing. The second moving mechanism has both the intersection angle adjusting mechanism and the offset mechanism.
In the present embodiment, the tilting frame 121 includes an offset control unit (illustration shown) that controls an offset amount in the casting direction (vertical direction) between the first cooling drum 100A and the second cooling drum 100B according to the intersection angle 2θ. None) is provided.

In the present embodiment, as shown in FIG. 3, the tilting frame 121 supporting the second cooling drum 100B is fixed on the gantry 111, and the tilting frame 121 supporting the first cooling drum 100A is The hydraulic cylinder 112 is arranged so as to be horizontally movable on the gantry 111 along a guide rail 113 provided on the gantry 111.
The guide rail 113 connects the first cooling drum 100A to the second cooling drum 100B while maintaining the state in which the rotation axis of the first cooling drum A100A and the rotation axis of the second cooling drum 100B are parallel when viewed from the vertical direction. It is configured to be able to approach and move away from it.

In the present embodiment, the guide rail 113 and the hydraulic cylinder 112 move at least one of the cooling drums 100 (the first cooling drum 100A) of the pair of cooling drums 100 in a direction orthogonal to the plate surface of the metal ribbon S (this embodiment). (In the horizontal direction).
In the early stage of casting, it is necessary to elastically press the first cooling drum 100A and the second cooling drum 100B against the metal ribbon S, while the thickness of the metal ribbon S is kept constant in the stable casting period. Therefore, the space between the first cooling drum 100A and the second cooling drum 100B needs to be firmly fixed. The moving mechanism of the first cooling drum 100A is not particularly limited, but both can be realized by switching the hydraulic circuit using the hydraulic cylinder 112 as in the present embodiment.

Further, in the present embodiment, as shown in FIGS. 3 to 5, a position detector 115 that detects the position of the first cooling drum 100A by the first moving mechanism is provided. The position detector 115 is configured to detect the position of the first cooling drum 100A based on a state in which the first cooling drum 100A and the second cooling drum 100B are in contact with each other. In addition, the position detector 115 may be a displacement meter provided in the hydraulic cylinder 112, for example.
Further, in the present embodiment, the load meters 116 are respectively provided on the tilting frames 121 of the second cooling drum 100B. Further, a pressure gauge 117 for measuring the pressure of the hydraulic cylinder 112 is provided.

  Further, in the present embodiment, as shown in FIG. 5, a thickness distribution measuring device 107 for measuring the width direction thickness distribution of the metal ribbon S is disposed downstream of the pair of cooling drums 100A and 100B. Then, according to the width direction thickness distribution of the metal ribbon S measured by the thickness distribution measuring device 107, the intersection angle 2θ between the rotation axis of the first cooling drum 100A and the rotation axis of the second cooling drum 100B, and The offset amount of the first cooling drum 100A and the second cooling drum 100B in the casting direction (vertical direction) is feedback-controlled.

Here, when the rotation axis of the first cooling drum 100A and the rotation axis of the second cooling drum 100B intersect, as shown in FIGS. 6 and 7, the first cooling drum 100A and the second cooling drum 100B Will be distributed in a quadratic curve in the width direction. The closest distance δ is calculated by the following equation, and the distribution of the closest distance δ in the axial direction (width direction) changes depending on the intersection angle 2θ. Here, in the figures and formulas, D is the diameter of the cooling drum, h is the distance between a pair of cooling drums in the horizontal direction (that is, in plan view), x is the distance from the center of the drum width in the drum width direction, and L is The drum length of the cooling drum.

  The intersection angle 2θ between the rotation axis of the first cooling drum 100A and the rotation axis of the second cooling drum 100B depends on the diameter and the trunk length of the first cooling drum 100A and the second cooling drum 100B, but is 3.0. ° is often sufficient. For example, when the drum body length is 1200 mm and the center-to-center distance of the chocks 103 at both ends of the width is 2000 mm, an inclination of 1.5 ° at the half angle of intersection θ corresponds to a height difference of about 52 mm at the chocks 103 at both ends of the width. If the rotation axis of the first cooling drum 100A and the tilting direction of the second cooling drum 100B are determined, for example, one chock 103 may have an adjustment range of 0 to 26 mm, and the other chock 103 may have an adjustment range of −26 to 0 mm.

Then, the first cooling drum 100A and the second cooling drum 100B cross each other, and the closest distance δ between the first cooling drum 100A and the second cooling drum 100B is distributed in a quadratic curve in the width direction. When the offset amount in the casting direction (vertical direction) of the first cooling drum 100A and the second cooling drum 100B is adjusted, the position of the minimum point of the quadratic curve moves from the center in the width direction as shown in FIG. Thereby, as shown in FIGS. 9 and 10, the closest approach distance δ between the first cooling drum 100A and the second cooling drum 100B has different values at both ends of the width.
As shown in FIG. 11, the amount of change in the closest distance δ due to the offset amount f changes depending on the intersection angle 2θ between the rotation axis of the first cooling drum 100A and the rotation axis of the second cooling drum 100B. Therefore, it is necessary to adjust the offset amount according to the intersection angle 2θ between the rotation axis of the first cooling drum 100A and the rotation axis of the second cooling drum 100B. Therefore, in the present embodiment, the above-described offset control unit is provided.

  In the twin-drum continuous casting apparatus 10 having the above-described configuration, the molten metal 3 is cooled by being brought into contact with the rotating cooling drums 100A and 100B, thereby forming a solidified shell on the peripheral surfaces of the cooling drums 100A and 100B. 5 and 5 are grown, and the solidified shells 5 and 5 formed on the pair of cooling drums 100A and 100B are pressed together at the closest point of the drum, thereby casting a metal ribbon S having a predetermined thickness.

  Here, the thermal expansion of the first cooling drum 100A and the second cooling drum 100B proceeds in a direction in which the center of the width becomes larger in diameter than the both ends as the casting proceeds. That is, the thermal crown grows. As a result, the gap distribution between the first cooling drum 100A and the second cooling drum 100B changes so that the width center gradually narrows. On the other hand, as the intersection angle 2θ between the first cooling drum 100A and the second cooling drum 100B increases, the drum gap at the center of the width decreases. Therefore, in order to compensate for the thermal crown growth of the first cooling drum 100A and the second cooling drum 100B, it is necessary to increase the initial value of the intersection angle 2θ and then gradually reduce it.

Note that the crown of the metal ribbon S is generally aimed at a shape whose center in width is slightly thicker than both ends, for reasons such as work stability in steps such as rolling after casting. It is preferable to predict the approximate growth amount of the thermal crown in advance and determine a sufficient intersection angle operation range to compensate for this.
Basically, the maximum angle of the operation range is set as the initial setting angle, and the first cooling drum 100A and the second cooling drum 100B are set so that the drum gap distribution at the initial setting angle matches the target crown of the metal ribbon S. It is preferable that the initial crown is formed in advance by polishing.

  Note that the target thickness and the target crown of the metal ribbon S may be intentionally changed at the start of casting and after stabilization. For example, at the start, in consideration of the stability of casting, the thickness may be slightly thicker and the crown larger than originally intended. This is also taken into account in the initial setting of the drum interval and the intersection angle 2θ and in the setting of the initial crown. After the casting is started, the operations of the first moving mechanism and the second moving mechanism are fed back based on the thickness and crown measurement results obtained by the thickness distribution measuring device 107 installed on the downstream side of the drum so that they coincide with the respective targets. Control.

  Here, if a wedge is detected, the offset is feedback-controlled in a direction to compensate for the wedge. When the offset is operated, the drum gap at the center of the width slightly changes. Since the amount of change is geometrically determined from the drum diameter and the offset amount, the distance between the cooling drums may be corrected and controlled at the same time as the offset operation, but since the amount of change is small, no particular consideration is given. There is no problem as a method of compensating by the feedback control for changing the operation of the first moving mechanism based on the measurement result of the thickness distribution measuring device 107.

  As described above, according to the twin-drum continuous casting apparatus and the method for manufacturing a metal ribbon according to the present embodiment, the difference in the thickness (crown) between the width center portion and the width end portion of the metal ribbon is adjusted by the intersection angle. By adjusting by a mechanism and adjusting the difference (wedge) of the thickness of both ends of the metal ribbon by an offset mechanism, a high-quality metal ribbon having a stable thickness distribution in the width direction can be manufactured. Even in the case where a change in the casting state occurs, it is possible to stably control with good response.

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

Next, experimental results confirming the effects of the present invention will be described.
In a twin-drum continuous casting apparatus having the same configuration as that of the above-described embodiment, low-carbon steel having a plate thickness of 2 mm was cast using a pair of cooling drums having a width center diameter of 800 mm and a body length of 1200 mm.
The distance between the chocks at both ends in the width direction is 2000 mm, and a total of four chocks that support both ends of the rotating shafts of the pair of cooling drums are accommodated in the tilting frame described in the embodiment. The gap between the pair of cooling drums can be adjusted by the opening / closing mechanism of one of the drums, and the other drum has no opening / closing mechanism, but is supported in a state where the reaction force received from the steel strip can be detected.

  In addition, a thickness distribution measuring instrument capable of simultaneously measuring the thickness of the steel strip at multiple points in the width direction was installed at a position 1000 mm below the closest point of the cooling drum. However, since the thickness at the extreme end of the steel strip width cannot be measured by the thickness distribution measuring device, the thickness at both ends of the steel strip width hereinafter refers to the thickness at a position close to the center of 75 mm from the extreme end.

  At the start of casting, the cooling drum is stationary while clamping the metal dummy sheet with a predetermined force, and starts rotating immediately after injecting molten steel from the tundish installed above the drum, Accelerated. The steel strip is cast following the dummy sheet and discharged downward. At this point, the cooling drum is pressed elastically, and the thickness of the steel strip changes greatly in accordance with the transient change in the casting state. Specifically, the thickness gradually decreases after passing through a local thickness portion also called a nodule. After the casting was stabilized, the pressing of the cooling drum was switched to open / close position control having high rigidity, and feedback control was performed based on the detection value of the thickness distribution measuring instrument so that the thickness of the central portion of the steel strip was 2.0 mm.

  The solidification of the steel strip proceeds from the surface layer in contact with the cooling drum, and almost the entire area of the thickness solidifies at the closest point of the pair of cooling drums. If the solidification is too slow, a break or the like will occur on the drum exit side, and if too early, an excessive reaction force will occur between the drums. For this reason, the drum reaction force was detected, and the rotation speed of the drum was adjusted so that the reaction value became an appropriate value. As a result, the steady state casting speed was 155 mpm.

  On the two cooling drums, concave initial crowns having a small diameter at the center in the width direction and large diameters at both ends in the width direction were formed in advance by polishing. The shape of the initial crown is a quadratic curve, and the diameter difference between the center of the width and both ends of the body length of 1200 mm is 140 μm, that is, the drum diameter is 800.00 mm at the center of the width and 800.14 mm at both ends in the width direction. At the start of casting, the left and right chocks of the cooling drum were provided with a height difference of 28.2 mm, so that the intersection angle 2θ was 1.616 °.

  The crown and wedge control of the steel strip by the crossing angle and the offset were performed when the pressing of the drum was switched to the open / close position control. The thickness at the center in the width direction of the steel strip is also controlled, but the description is omitted here. Table 1 shows a representative example of the control situation. Originally, the control is performed continuously, but intermittent control that intentionally repeats turning on and off is performed so that the crown and wedge changes before and after the control are made clear.

In the example in the early stage of casting, the crown of the steel strip was 57 μm and the wedge was −36 μm (right thickness <left thickness). Thus, by changing the crossing angle 2θ from 1.616 ° to 1.742 °, the crown could be controlled to the target 30 μm. Also, the wedge could be controlled to 2 μm by setting the offset to 0.8 mm.
Thereafter, the intersection angle was gradually reduced in accordance with the thermal crown growth of the drum. When the control was interrupted again in the middle stage of casting, the crown of the steel strip was 13 μm and the wedge was 25 μm (right thickness> left thickness). Thus, by changing the crossing angle 2θ from 0.768 ° to 0.586 °, it was possible to control the crown to 31 μm, almost as intended. Also, the wedge could be controlled to -1 μm by setting the offset from 0.1 mm to -1.6 mm.
At the end of casting, the intersection angle 2θ was 0.642 °, the offset was -1.3 mm, the crown of the steel strip was 28 μm, and the wedge was 0 μm.

  In this control, the wedge of about 0.03 mm was able to be controlled by changing the height position of the chock by about 1 mm. In the case where the opening and closing of the chocks at both ends in the width direction are individually adjusted as in the conventional method, the opening and closing can be precisely performed in substantially the same order (in the case of this apparatus, about 2000/1200 = 1.7 times). You need to control. There is a great difference in the accuracy required of the control mechanism, and it is practically difficult to control a wedge of about 0.03 mm by the individual opening and closing type of the chocks at both ends in the width direction due to the accuracy limit of the apparatus.

  On the other hand, the overall thickness control with the center in the width direction of the steel strip as a representative point is performed by a drum opening / closing device, and exactly the same order of adjustment is required, but since the steel strip is subsequently rolled, the overall thickness is When can be controlled. On the other hand, if a wedge remains and is intended to be removed in the rolling step, a half-extended shape or meandering is caused, which makes the rolling operation difficult. Therefore, it is extremely effective that the wedge can be adjusted by means of high controllability at the casting stage.

S metal ribbon 10 twin-drum continuous casting apparatus 100A first cooling drum 100B second cooling drum

Claims (6)

A twin-drum continuous casting apparatus for producing a metal ribbon by solidifying a molten metal by a pair of rotating cooling drums,
A first moving mechanism for moving at least one of the pair of cooling drums in a direction perpendicular to the plate surface of the metal ribbon, and a pair of the cooling drums being parallel to the plate surface of the metal ribbon. And a second moving mechanism for moving in the direction,
The second moving mechanism tilts a rotation axis of the cooling drum in a plane parallel to a plate surface of the metal ribbon, and adjusts an intersection angle of the pair of cooling drums; An offset mechanism that adjusts an offset amount in the casting direction of the pair of cooling drums while maintaining an intersection angle of the cooling drum, and an offset control unit that controls an offset amount of the pair of cooling drums according to the intersection angle. , A twin-drum continuous casting apparatus.   2. The twin-drum continuous casting apparatus according to claim 1, wherein in the second moving mechanism, the intersection angle adjusting mechanism and the offset mechanism are configured by a common mechanism. 3.   The first moving mechanism moves at least one of the cooling drums while keeping the rotation axes of the pair of cooling drums parallel to each other in a plane perpendicular to the plate surface of the metal ribbon. The twin-drum continuous casting apparatus according to claim 1 or 2, further comprising a guide portion that moves in a direction perpendicular to the plate surface of the band.   The thickness distribution measuring device which measures the width direction thickness distribution of the said metal ribbon in the downstream of the said pair of cooling drums is arrange | positioned, The Claim 1 characterized by the above-mentioned. The twin-drum continuous casting apparatus as described in the above. A method for producing a metal ribbon using the twin-drum continuous casting apparatus according to any one of claims 1 to 4,
The difference in thickness between the width center portion and the width end portion of the metal ribbon is adjusted by the intersection angle adjustment mechanism, and the difference in thickness between both end portions of the metal ribbon is adjusted by the offset mechanism. Manufacturing method of metal ribbon. Using the twin-drum continuous casting apparatus according to claim 4, the thickness distribution measuring device measures the width direction thickness distribution of the metal ribbon,
The intersection angle adjustment is performed so that the difference in thickness between the width center portion and the width end portion of the metal ribbon becomes a predetermined target value, and the difference in thickness between both end portions of the metal ribbon becomes small. The method according to claim 5, wherein the mechanism and the offset mechanism are feedback-controlled.

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