The present invention relates to a method for casting a slab.
　The present application claims priority based on Japanese Patent Application No. 2018-198355 filed in Japan on October 22, 2018, the contents of which are incorporated herein by reference.
Background technology
[0002]
　For the production of metal strips (hereinafter referred to as slabs), for example, as shown in Patent Document 1, a twin drum type continuous casting apparatus is used. In the twin-drum type continuous casting apparatus, a pair of continuous casting casting drums (hereinafter referred to as casting drums) are arranged in parallel, and the facing peripheral surfaces are rotated from above to downward, respectively, and formed by the peripheral surfaces of these casting drums. The molten metal is injected into the pooled portion of the molten metal, and the molten metal is cooled and solidified on the peripheral surface of the casting drum to continuously cast the metal strip. The pair of casting drums press the slab with a predetermined pressing force while maintaining the parallelism of the rotation axes during casting. The reaction force from the slab to the casting drum changes depending on the solidification state and may become non-uniform in the width direction, and it is difficult to strictly maintain the parallelism of the rotation axes of the pair of casting drums. For this reason, a difference in plate thickness at both ends in the width direction, so-called wedge, may occur in the slab. When wedges are generated, meandering may occur in the rolling process arranged downstream of the casting drum, which may cause rolling defects.
[0003]
　For example, as a method for suppressing the generation of wedges, Patent Document 1 states that while maintaining a state in which a pair of casting drums are parallel to each other, the opening / closing, crossing angle, and offset amount of the casting drums are controlled to crown the slab. And techniques for adjusting wedges are disclosed.
[0004]
　Patent Document 2 describes a twin-drum type continuous casting machine that casts a molten metal into the surface gaps of two drums that have parallel rotation axes and hold arbitrary gaps and rotate in opposite directions to cast a thin plate. A reduction control method is disclosed. In this method, the pressing forces at both ends of one drum are detected and added, and a signal based on this is used to hydraulically cylinder both ends of the other drum so that the sum of the pressing forces at both ends of one drum becomes a predetermined value. Wedges are reduced by moving them in parallel.
[0005]
　In Patent Document 3, molten metal is poured between a pair of rotating rolls or one of the rolls, and the solidified shell of the molten metal formed on the long side of the roll is compressed by a double roll. Then, a method for continuously casting a thin strip plate for continuously producing the thin strip plate is disclosed. In this method, the plate thickness is controlled by detecting the compressive load acting on the rotating rolls and controlling the solidification time between the rolls so that this value becomes a target value.
[0006]
　In Patent Document 4, the reduction load when the solidified shell is crimped in the gap between the roll pairs is continuously measured, and the rotation speed of the roll pair is controlled so that the measured reduction load is maintained at the target load. The technology is disclosed. In such a method, the plate thickness is controlled by controlling the rotation speed of the roll pair.
[0007]
　Further, in Patent Document 5, in the rolling mill reduction setting control method, when the plate thickness is obtained when a plate thickness gauge is not installed, the contribution of each roll deformation and the contribution other than the roll deformation are separated. It is disclosed that the mill elongation is predicted and the plate thickness is estimated.
Prior art literature
Patent documents
[0008]
Patent Document 1: Japanese Patent Application Laid-Open No. 2017-196636
Patent Document 2: Japanese Patent Application Laid-Open No. 62-323710
Patent Document 3: Japanese Patent Application Laid-Open No. 58-1738337
Patent Document 4: Japanese Patent Application Laid-Open No. 62-323710 No. 62-123658
Patent Document 5: Japanese Patent Application Laid-Open No. 60-030508
Outline of the invention
Problems to be solved by the invention
[0009]
　However, in order to control the wedge with higher accuracy, in the technique described in Patent Document 1, a thickness distribution meter or the like for measuring the plate thickness is installed downstream of the casting direction of the casting drum, and the measurement result is obtained by the cylinder of the casting drum. It is necessary to control the plate thickness by feeding back to the position and the like. When installing the thickness distribution meter, it is desirable to be as close as possible to the casting equipment in order to reduce wasted time. However, if a thickness distribution meter is installed directly under the casting apparatus, if the molten metal fails to be drawn out, the molten metal may fall on the thickness distribution meter and damage the thickness distribution meter. Therefore, the thickness distribution meter needs to be installed at a position farther from the casting drum. According to this, since the waste time becomes large, it is difficult to perform feedback control of the wedge with high accuracy according to the measured plate thickness.
[0010]
　In the technique described in Patent Document 2, the rigidity of the cast drum is not always equal at both ends, and even if the cast drum is moved in parallel by the hydraulic cylinder so as to aim at the sum of the pressing forces, the wedge is reduced. Not exclusively.
[0011]
　The technique described in Patent Document 3 aims to control the average plate thickness of the material, and the average plate thickness can be kept within a predetermined range, but the wedge cannot be reduced.
[0012]
　In the technique described in Patent Document 4, the average plate thickness of the slab can be kept within a predetermined range, as in the technique disclosed in Patent Document 3, but the wedge cannot be reduced.
[0013]
　The present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved method for casting slabs, which can reduce wedges more accurately.
Means to solve problems
[0014]
(1) In the slab casting method according to one aspect of the present invention, the slab is cast using a twin-drum continuous casting apparatus that solidifies molten metal with a pair of rotating casting drums to produce the slab. Using the casting drum housing reduction system deformation characteristics that show the deformation characteristics of the housing that supports the casting drum and the deformation characteristics of the reduction system that reduces the casting drum, which were acquired before the start, the slab of the slab can be obtained from the following equation 1. The estimated plate thickness at both ends in the width direction is calculated, and the reduction positions of the cylinders provided at both ends in the width direction of the casting drum are controlled so that the difference between the estimated plate thicknesses at both ends is equal to or less than a predetermined value. do.
　However, in Equation 1, the cylinder reduction position and the casting drum housing reduction system deformation represent the differences from the reduction position zero point adjustment, respectively.
　(Estimated plate thickness) = (Cylinder reduction position)
　　　　+ (Casting drum elastic deformation)
　　　　+ (Casting drum housing reduction system deformation)
　　　　+ (Casting drum drum profile)
　　　　-(Casting drum elastic deformation when adjusting the reduction position zero point ) ) ・ ・ ・ ・ ・ Equation 1
[0015]
　With the above configuration, the estimated plate thickness at both ends in the width direction of the slab is calculated, and the reduction position of the cylinders provided at both ends of the casting drum is controlled so that the difference between the estimated plate thicknesses is equal to or less than a predetermined value. By doing so, it is possible to cast the slab in a shorter time than by actually measuring the slab after casting and controlling the plate thickness of the slab at the time of casting.
[0016]
(2) In the slab casting method according to (1) above, the casting drum housing reduction system deformation characteristic opens a pair of side dams provided at the widthwise ends of the casting drum, and the casting drum. It may be obtained based on the reduction position and the load of the cylinder obtained by performing tightening in a state where a plate having a plate width longer than the drum length of the casting drum and a plate thickness having a uniform thickness is sandwiched between the two. ..
[0017]
(3) In the method for casting a slab according to (1) or (2) above, the reduction position zero adjustment of the casting drum opens a pair of side dams provided at the widthwise end of the casting drum. Therefore, a plate having a plate width longer than the drum length of the casting drum and a plate thickness having a uniform thickness may be sandwiched between the casting drums.
The invention's effect
[0018]
　As described above, according to the present invention, the wedge of the slab can be reduced more accurately.
A brief description of the drawing
[0019]
FIG. 1 is a schematic cross-sectional view showing a continuous casting facility according to an embodiment of the present invention.
[Fig. 2] Fig. 2 is a schematic view showing an example of the configuration of a casting drum.
FIG. 3 is a schematic plan view showing a state of meandering of slab S in a rolling mill.
FIG. 4 is a schematic view showing a cross section of an example of a slab in which meandering occurs in a rolling mill.
[Fig. 5] Fig. 5 is a schematic view showing the generation of wedges in a casting drum.
[Fig. 6] Fig. 6 is a schematic view showing an example of adjusting the reduction position zero point of a casting drum.
[Fig. 7] Fig. 7 is a schematic view showing an example of adjusting the reduction position zero point of a casting drum.
FIG. 8 is a schematic view showing an example of adjusting the reduction position zero point of a casting drum.
[Fig. 9] Fig. 9 is a schematic view showing an example of the configuration of a casting drum.
[Fig. 10] Fig. 10 is a schematic view showing an example of acquiring the deformation characteristics of a casting drum housing reduction system.
Mode for carrying out the invention
[0020]
　Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.
[0021]
　In the present specification, the numerical range represented by using "-" means a range including the numerical values ​​before and after "-" as the lower limit value and the upper limit value. In the present specification, the term "process" is used not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. included. Further, it is obvious that each element of the following embodiment can be combined with each other.
[0022]
　
　First, with reference to FIGS. 1 to 5, an outline of a casting method of slabs will be described by giving an example of a continuous casting facility for manufacturing slabs.
[0023]
　(Continuous Casting Equipment)
　First, an outline of a slab casting method using the continuous casting equipment 1 will be described with reference to FIG. FIG. 1 is a diagram showing an example of a continuous casting facility 1 to which the present invention is applied. The continuous casting equipment 1 includes a twin drum type continuous casting device 100 (hereinafter referred to as a continuous casting device 100), a first pinch roll 20, a rolling mill 30, a second pinch roll 40, and a winding device 50. , Equipped with.
[0024]
　The continuous casting apparatus 100 has a pair of casting drums including a first casting drum 111 and a second casting drum 112. The pair of casting drums are arranged so as to face each other in parallel in the horizontal direction. The continuous casting apparatus 100 rotates the first casting drum 111 and the second casting drum 112 in different circumferential directions R1 and R2 so that the facing surfaces of the pair of casting drums are extended downward, and these casting drums The molten metal is injected into the pooled portion formed by the peripheral surface of the casting drum, and the molten metal is cooled and solidified on the peripheral surface of the casting drum to continuously cast the slab S.
[0025]
　The continuous casting apparatus 100 will be described in detail with reference to FIG. FIG. 2 is a diagram showing details of the continuous casting apparatus 100 from the axial direction of the casting drum. As shown in FIG. 2, the continuous casting apparatus 100 includes a pair of casting drums including a first casting drum 111 and a second casting drum 112, and a pair of first casting drums 111 and a second casting drum 112 in the width direction. Holds the side weir 150 disposed in the portion and the metal molten metal 117 supplied to the metal molten metal pool 115 defined by the pair of the first casting drum 111, the second casting drum 112, and the side weir 150. The tundish 113 and a dipping nozzle 114 for supplying the molten metal 117 from the tundish 113 to the molten metal reservoir 115 are provided.
[0026]
　In such a continuous casting apparatus 100, the peripheral surfaces of the first casting drum 111 and the second casting drum 112 are cooled by contacting the rotating first casting drum 111 and the second casting drum 112 to cool the molten metal 117. The solidification shell 116 grows on the solidification shell 116, and the solidification shells 116 formed on the pair of casting drums are crimped at the closest points of the pair of casting drums to cast a slab S having a predetermined thickness.
[0027]
　In the continuous casting apparatus 100, the casting drum is generally at a low temperature before the start of casting. When casting is started, the temperature of the casting drum rises due to contact with a hot molten metal. Further, the casting 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 casting drum reaches a certain level is called the steady casting, and the temperature of the casting drum during the steady casting is called the steady temperature.
[0028]
　Here, as shown in FIG. 1, the slab S cast from the continuous casting apparatus 100 is sent to the rolling mill 30 by the first pinch roll 20.
[0029]
　The rolling mill 30 rolls the slab S to a desired plate thickness. The rolling mill 30 includes an upper work roll 31 and a lower work roll 32, and an upper backup roll 33 and a lower backup roll 34 that support the upper work roll 31 and the lower work roll 32, respectively.
[0030]
　The slab S rolled to a desired plate thickness by the rolling mill 30 is sent to the winding device 50 by the second pinch roll 40, and is wound into a coil by the winding device 50.
[0031]
　(Meandering in a rolling mill) In
　the rolling mill 30 of the continuous casting facility 1 as described above, meandering may occur in which the through-plate position of the slab S moves in the direction perpendicular to the rolling direction. Here, FIG. 3 is a schematic plan view showing the state of meandering of the slab S in the rolling mill 30, and is a view of the plate surface of the slab S from the upper work roll 31 side. The slab S rolled by the upper work roll 31 and the lower work roll 32 does not advance parallel to the rolling direction and meanders. Such meandering occurs when one side and the other side are asymmetrically rolled in the width direction of the upper work roll 31 and the lower work roll 32. The one side and the other side of the rolling mill may mean the driving side on which the motor of the rolling mill is driven and the working side opposite to the driving side, which will be described later.
[0032]
　Such meandering of the slab S may occur due to the shape of the plate thickness of the slab S before being rolled by the rolling mill 30. FIG. 4 shows an example of a cross-sectional view of a slab that generates meandering in a longitudinal direction (transportation direction). In the slab S, the plate thickness t 1 at one end is thicker than the plate thickness t 2 at the other end, and the plate thickness gradually changes from one end to the other in the width direction. When such a slab S having a non-uniform plate thickness is rolled, the thick portion is stretched more than the thin portion. Rolling reduction, thickness t at the inlet side 2 plate thickness t than the side 1 increases in towards the ends of the side. In this case, the material velocity on the entry side becomes smaller at the end on the plate thickness t 1 side than on the plate thickness t 2 side, and the difference in entry speed between one end and the other end of the slab S, that is, the slab S Meandering occurs due to the rotation in the plane of.
[0033]
　More specifically, since the total amount of the material of the slab S is the same on the entry side and the exit side of the rolling mill, the value obtained by multiplying the speed of the slab S and the plate thickness is the entry side and the exit side of the rolling mill. Will be the same. At this time, when the outer plate thickness is uniform in the width direction, if there is a difference in the plate thickness between one end and the other end of the slab S on the inlet side of the rolling mill, a difference in rolling rate occurs, for example, the inlet plate thickness is thick. The entry speed is lower at the end than at the end where the entry side plate thickness is low. As a result, the end portion having a high entry speed is drawn into the work roll faster than the end portion having a low entry speed and rolled, a rotation speed is generated in the slab S, and meandering in the rolling mill occurs.
[0034]
The generation of wedges, which is the difference between the 　plate thickness t 1 and the plate thickness t 2 shown in FIG. 4, will be described in detail later. This occurs because the wedges are not accurately reduced in the casting drum during casting. Therefore, in order to reduce the meandering in the rolling mill 30, it is effective to accurately reduce the wedges generated in the continuous casting apparatus 100.
[0035]
　(Generation of Wedges in Casting Drum) With
　reference to FIG. 5, the generation of wedges in the continuous casting apparatus 100 will be described. FIG. 5 is a plan view of the continuous casting apparatus 100 as viewed from directly above the continuous casting apparatus 100 in the casting direction.
[0036]
　FIG. 5 is a diagram showing a state of the continuous casting apparatus 100 when a wedge is generated in the slab S. As shown in FIG. 5, when the slab S is cast in a state where the rotary shaft Ar1 and the rotary shaft Ar2 of the first casting drum 111 and the second casting drum 112 are not parallel, the slab S is cast as shown in FIG. The plate thickness of S changes in the width direction to generate a wedge.
[0037]
　Here, with reference to FIGS. 6 to 8, an example of a factor in which casting is performed without the rotation axes of the first casting drum 111 and the second casting drum 112 being parallel to each other will be described. 6 to 8 are views schematically showing the casting drum at the time of adjusting the reduction position zero point before the start of casting as viewed from directly above the casting drum in the casting direction of the casting drum.
[0038]
　As shown in FIGS. 6 to 8, the plate profile of the casting drum before the start of casting has a concave shape in the plate width direction. In FIGS. 6 to 8, the concave shape of the profile is emphasized for the sake of explanation. This is because the first casting drum 111 and the second casting drum 112 thermally expand and change with the elapsed time from the start of casting to the arrival at the time of steady casting. In the casting drum, the initial profile of the casting drum is set so that the plate profile (crown) of the metal strip at the time of steady casting in which thermal expansion is observed becomes the desired plate profile. Specifically, the drum diameter at the center of the width of the casting drum is set to a concave crown that is smaller than the drum diameter at both ends of the casting drum.
[0039]
　In a casting drum to which such a concave crown is provided, the reduction position zero point can be adjusted by contacting (kissing) the pair of casting drums with each other and setting the reduction position (pressing position) when a predetermined load F is applied to zero. Will be done. By adjusting the zero point of the reduction position, the initial value of the reduction position of the cylinder that reduces the casting drum can be set.
[0040]
　However, the cast drum is provided with a concave crown as described above. Therefore, when the casting drums are brought into contact (kiss) with each other and a predetermined load F is applied to the casting drums, only both ends of the casting drums come into contact with each other. Therefore, for example, as shown in FIG. 6, when the positions of the casting drums in the width direction do not completely match, when a predetermined load F is applied to the casting drum, the first casting drum 111 The contact points between both ends and both ends of the second casting drum 112 are displaced, and an amount of deviation x is generated, resulting in an unstable state. Therefore, the accuracy of the reduction position zero adjustment is lowered.
[0041]
　In order to avoid this, when the reduction position zero point is adjusted using the casting drum provided with the concave crown, the reduction position zero adjustment is performed by sandwiching the thin plate 118 between the casting drums as shown in FIG. In FIG. 7, the midpoint 118C of the length of the thin plate 118 in the width direction is arranged on a straight line connecting the midpoint 111C and the midpoint 112C of the length of the first casting drum 111 and the second casting drum 112 in the width direction. An example is shown in which both ends of the casting drum do not shift. If no deviation occurs, the rotation shaft Ar1 and the rotation shaft Ar2 of the first casting drum 111 and the second casting drum 112 are parallel to each other, so that the reduction position zero point adjustment can be stably performed.
[0042]
　However, even when the thin plate 118 is sandwiched between the casting drums and the reduction position zero point is adjusted, as shown in FIG. 8, the intermediate point 118C of the length in the width direction of the thin plate 118 is the first casting drum 111 and the first casting drum 111. 2 The thin plate 118 is not arranged on the straight line connecting the intermediate points 111C and 112C of the length in the width direction of the casting drum 112, and the thin plate 118 is arranged closer to one end of the casting drum in the width direction. be. In this case, since the rotation shaft Ar1 and the rotation shaft Ar2 of the first casting drum 111 and the second casting drum 112 are not parallel to each other, even if the reduction position zero point is adjusted, the left and right (the first casting drum 111 and the second casting drum 112 There is an error at both ends in the width direction). When casting is performed in such a state, wedges are generated in the slab to be cast when the cylinder is controlled at the reduced position.
[0043]
　In order to reduce the meandering of the slab when passing through the rolling mill, the present inventors set the thickness of the slab cast by the casting drum at both ends in the width direction of the slab in order to reduce the wedge as described above. A method of controlling the plate thickness of the slab to be cast was examined based on the estimated plate thickness.
[0044]
　Here, the estimation of the plate thickness will be described. For example, as shown in Patent Document 5, in a rolling mill, when determining the plate thickness when a plate thickness gauge is not installed, the contribution of each work roll deformation and the contribution of deformation other than the work roll are used. The plate thickness may be estimated by separating into. Specifically, in the rolling mill, the length of the work roll in the width direction is longer than the plate width of the slab, the gaps at both ends of the work roll in the rolling mill are estimated, and the average of the gaps at both ends is used. Therefore, the plate thickness at the center of the roll barrel is calculated. In the rolling mill, since the load can be stably applied when the reduction position zero point is adjusted, the reduction position zero point adjustment can be performed without error. In this way, the gaps at both ends are used to accurately adjust the plate thickness at the center of the slab. Can be estimated.
[0045]
　However, in the rolling mill, it is not possible to grasp the position of the slab sent out from the continuous casting apparatus in the width direction of the rolling mill. Therefore, even if the gap between the work rolls in the rolling mill can be estimated, it is not possible to grasp the position of the gap corresponding to both ends of the slab, and the plate thickness of both ends of the slab can be determined. Cannot be estimated. Therefore, in the rolling mill, it was not possible to estimate the wedges at both ends of the slab using the estimated plate thickness.
[0046]
　On the other hand, in the casting drum, as shown in FIG. 5, the slab is cast by being surrounded by the first casting drum 111 and the second casting drum 112, and the side weirs 150 provided at both ends in the width direction of the casting drum. NS. Therefore, the length in the width direction (barrel length) of the slab and the casting drum match. Focusing on this event, the inventors applied the plate thickness estimation in the rolling mill to the casting drum, estimated the plate thickness at both ends of the slab, and based on the estimated plate thickness, of the casting drum. I came up with the idea that the wedge can be reduced by controlling the pressing means.
[0047]
　(Structure of Continuous Casting Equipment) With
　reference to FIG. 9, a configuration example of a casting drum for carrying out the method of casting a slab according to an embodiment of the present invention will be described. FIG. 9 is a plan view showing an example of configuration details of the continuous casting apparatus as viewed from directly above in the casting direction.
[0048]
　The first casting drum 111 and the second casting drum 112 are arranged so as to face each other in the horizontal direction, and a slab is cast between the first casting drum 111 and the second casting drum 112. The first casting drum 111 and the second casting drum 112 are rotated by the drive of the motor M, and the slab S is sent downstream in the casting direction. Hereinafter, in the present specification, in the width direction of the casting drum of the continuous casting apparatus 100, the drive side by the motor M is referred to as a drive side DS, and the side opposite to the drive side is referred to as a work side WS. Later, the thickness t of the drive side DS DS plate thickness t of the work side WS from WS a value obtained by subtracting the wedge (t DS -T WS described as).
[0049]
　In the continuous casting apparatus 100, the side dams 150d and the side dams 150d so as to surround the gaps formed by the first casting drum 111 and the second casting drum 112 facing each other at both ends of the first casting drum 111 and the second casting drum 112 in the width direction. A side weir 150w is provided. The molten metal is stored in the region surrounded by the first casting drum 111 and the second casting drum 112, and the side weir 150d and the side weir 150w, and the slab S is sequentially cast.
[0050]
　Both ends of the widthwise axis of the first casting drum 111 and the second casting drum 112 are supported by the housing 130d and the housing 130w, respectively. Both ends of the axis of the second casting drum 112 in the width direction are connected to the cylinder 120d and the cylinder 120w in the direction in which the casting drum faces and on the side opposite to the side on which the first casting drum 111 is arranged. The cylinder 120d and the cylinder 120w can move in the direction in which the casting drum faces each other. The second casting drum 112 is reduced by the cylinder 120d and the cylinder 120w to the side where the first casting drum 111 is arranged in the direction in which the casting drums face each other at both ends of the second casting drum 112. The cylinder 120d and the cylinder 120w can independently control both ends of the second casting drum 112.
[0051]
　At both ends of the shaft of the first casting drum 111, load cells 140d and load cells 140w for measuring the load applied to the first casting drum 111 are provided on the side opposite to the side on which the cylinder 120d and the cylinder 120w are arranged, respectively. Thereby, the load due to the reduction of the cylinder 120d and the cylinder 120w can be measured respectively.
[0052]
　(Estimation
　of Plate Thickness ) Next, a method of estimating the plate thickness of both ends indicated by the drive side end Sd and the work side end Sw of the slab cast by the continuous casting apparatus 100 described above will be described. do. The end Sd of the slab and the end Sw of the slab indicate an end region including at least one end of the casting drum.
[0053]
　Here, as an example of plate thickness estimation, plate thickness estimation of the end portion Sd of the slab will be described as an example. The plate thickness is estimated from the drum gap of the casting drum. The drum gap of the casting drum changes depending on the cylinder reduction position, the load applied to the casting drum, the contact with the slab, and the like. Changes in the drum gap due to the load applied to the casting drum, contact with the slab, etc. are the contribution of elastic deformation of the casting drum, the contribution of elastic deformation other than the drum, and the contribution of the change in the drum profile of the casting drum. Can be considered separately in. The contribution of elastic deformation other than the casting drum is called the casting drum housing reduction system deformation. Based on these elastic deformation amounts and the rolling position of the cylinder, the estimated plate thickness of the end Sd can be estimated by the following equation 1.
[0054]
　(Estimated plate thickness) = (Cylinder reduction position) + (Casting drum elastic deformation)
　　　　+ (Casting drum housing reduction system deformation)
　　　　+ (Casting drum drum profile)
　　　　-(Casting drum elastic deformation when adjusting the reduction position zero point ) ) ・ ・ ・ ・ ・ Equation 1
[0055]
　However, in Equation 1, the cylinder reduction position and the casting drum housing reduction system deformation represent the differences from the reduction position zero point adjustment, respectively. The difference may be a deviation from the cylinder reduction position at the time of adjusting the reduction position zero point and the deformation of the cast drum housing.
[0056]
(Cylinder reduction position) The
　cylinder reduction position indicates the position of the cylinder in the direction in which the cylinder 120d of the continuous casting apparatus 100 moves. For example, the reduction position of the cylinder indicates the position due to the difference from the initial value, which is the zero point where the cylinder position is adjusted to the zero point. The reduction position of the cylinder can be obtained from the displacement in the direction along the arrow a in FIG. The reduction position of the cylinder can be timely measured by a position sensor or the like (not shown) capable of measuring the movement amount of the cylinder 120d (or the cylinder 120w).
[0057]
(Elastic Deformation
　of Casting Drum ) The elastic deformation of the casting drum at the time of casting indicates the elastic deformation of the casting drum at an arbitrary time from the start of casting to the end of casting. In the casting drum, the shaft of the casting drum is bent or the casting drum is flattened due to the reaction force from the slab that comes into contact with the casting drum or the influence of the external force applied to the casting drum. These deformations are called elastic deformations of the casting drum during casting. The elastic deformation of the cast drum can be obtained by means such as analysis using the elastic theory.
[0058]
　For example, the bending of the shaft of the casting drum due to the contribution of the drum deformation of the casting drum can be calculated from the deflection calculation of the beam of the strength of materials by regarding the casting drum as a support beam at both ends. Regarding the load distribution in the width direction used in the deflection calculation, there is no problem assuming a linear distribution in the width direction based on the load cell values ​​provided at both ends of the shaft of the casting drum.
[0059]
(Casting drum housing reduction system deformation) The
　casting drum housing reduction system deformation characteristics are the characteristics that the housing 130d and the housing 130w are deformed under the influence of the reduction load applied to the casting drum, and the casting drum including the cylinder 120d and the cylinder 120w. The deformation characteristics including the deformation characteristics of the configuration that reduces the pressure are shown. For example, the method described in Patent Document 5 can be used to determine the deformation characteristics of the casting drum housing reduction system. The deformation of the casting drum housing reduction system can be calculated based on the load measured by the load cell 140d (or the load cell 140w) or the like, as will be described later.
[0060]
(Drum Profile of
　Casting Drum ) The drum profile of a casting drum is an index indicating the amount of thermal expansion of the casting drum or the amount of wear of the casting drum. In the drum profile of a casting drum, the amount of thermal expansion is calculated by calculating the amount of deformation of the surface shape of the casting drum based on the heat applied to the casting drum. The amount of wear may be measured from the drum profile before casting or estimated from the casting conditions. For example, since the surface shape at the time of designing a cast drum is known, the amount of deformation of the drum profile can be obtained by adding the shape deformation due to thermal expansion and wear to the surface shape.
[0061]
(Elastic deformation of the casting drum when adjusting the reduction position zero point) The elastic deformation
　of the casting drum when adjusting the reduction position zero point is the casting when adjusting the reduction position zero point, which determines the initial value of the reduction position of the casting drum before the start of casting. Shows the elastic deformation of the drum. Since the reduction position zero adjustment is performed with a load applied to the casting drum, elastic deformation occurs in the casting drum. The amount of elastic deformation at that time is defined as the elastic deformation of the casting drum when the reduction position zero is adjusted. This amount of elastic deformation can be calculated from the calculation of the deflection of the beam of the strength of materials in which the drum is regarded as the support beam at both ends, similar to the elastic deformation of the casting drum at the time of casting.
[0062]
　As described above, the estimated plate thickness is "casting" from the sum of the values ​​of "cylinder reduction position", "elastic deformation of casting drum", "casting drum housing reduction system deformation", and "drum profile of casting drum". It is obtained by reducing the value of "elastic deformation of the casting drum when adjusting the reduction position zero point of the drum".
[0063]
　(Acquisition of Deformation Characteristics of Casting Drum Housing Reduction System) Of the
　above-mentioned items of Equation 1, the deformation characteristics of the casting drum housing reduction system, which shows the deformation characteristics of configurations other than the drum, are delicate on the contact surface especially in the low load region. It is difficult to grasp the geometric shape exactly using a known physical model because it depends greatly on the shape and the characteristics are easily changed. Therefore, the estimated plate thickness can be obtained more accurately by acquiring the deformation characteristics of the casting drum housing reduction system using the method described later.
[0064]
　In the present embodiment, the casting drum housing reduction system deformation characteristic of the formula 1 is acquired before the casting of the slab is started. A method of acquiring the deformation characteristics of the casting drum housing reduction system will be described with reference to FIG. FIG. 10 is a diagram showing an example of a method for acquiring the deformation characteristics of the casting drum housing reduction system.
[0065]
　As shown in FIG. 10, acquisition of the casting drum housing reduction system deformation characteristic is performed by sandwiching the test plate 160 between the first casting drum 111 and the second casting drum 112. The length of the test plate 160 in the longitudinal direction is longer than the barrel length in the width direction of the casting drum, and the plate thickness is uniform. From this state, the test plate 160 is pressed by the first casting drum 111 and the second casting drum 112 by pressing and tightening the cylinder 120d and the cylinder 120w. The length of the test plate 160 in the direction perpendicular to the longitudinal direction is not limited, but the first casting drum 111 and the second casting drum are sufficiently contacted with the first casting drum 111 and the second casting drum 112. It is more preferable that the length is about 50 to 100 cm, which is about twice the drum diameter of 112.
[0066]
　By using the test plate 160 longer than the barrel length in this way, it is possible to apply an even load to both ends of the casting drum, and it is possible to accurately acquire the deformation characteristics of the casting drum housing reduction system. The deformation characteristic of the casting drum housing reduction system indicates the relationship between the load change and the deformation amount of the casting drum housing reduction system. As a result, the influence of the amount of deformation in which the reduction system including the casting drum housing, the cylinder, and the like is deformed according to the load applied to the casting drum during casting can be accurately reflected in the estimated plate thickness.
[0067]
　Specifically, the test plate 160 is sandwiched between the casting drums and the first casting drum 111 and the second casting drum 112 are not rotated. The casting drum is tightened with respect to the test plate 160 with a predetermined load larger than the load at the time of zero point adjustment, the reduction position of the casting drum and the load measured by the load cells 140d and 140w are acquired, and at each load. Calculate the amount of deformation of the casting drum. Then, by subtracting the amount of deformation of the casting drum from the rolling position of the casting drum, the amount of deformation of the casting drum housing reduction system for each load is acquired. As a result, it is possible to obtain the amount of deformation of the casting drum housing reduction system according to the load applied to the slab S when the slab S is cast.
[0068]
　As another method, the first casting drum 111 and the second casting drum 112 are rotated with the test plate 160 sandwiched between them, and the casting drum is tightened with the above-mentioned predetermined load for a predetermined time. The load is held, and the average value between the load and the rolling position of the casting drum is obtained. After that, the load of the casting drum is further changed, the changed load is held for a predetermined time, and the average value between the load of another level and the reduction position of the casting drum is obtained. Here, the time for holding each load may be two rotations of the casting drum. Further, this average value may be calculated from the time-series data of the load and the reduction position by acquiring the time-series data. In this way, the amount of deformation of the casting drum under each load is calculated, and the amount of deformation of the casting drum is reduced from the rolling position of the casting drum, so that the amount of deformation of the casting drum housing reduction system for each load is obtained.
[0069]
　The test plate 160 is formed of, for example, a material softer than the first casting drum 111 and the second casting drum 112 so as not to crush the dimples and the like formed on the surfaces of the first casting drum 111 and the second casting drum 112. Is more preferable. The test plate 160 is more preferably formed of, for example, an aluminum alloy, without limitation.
[0070]
　The deformation characteristics of the casting drum housing reduction system need only be acquired once before the start of a series of casting operations. Further, by performing this when a part of the structure of the housing or the reduction system is replaced, it is possible to acquire the deformation characteristics of the reduction system of the cast drum housing according to the equipment condition.
[0071]
　Further, in the reduction position zero adjustment, as shown in FIG. 10, a pair of side dams provided at the widthwise end of the casting drum is opened, and the plate thickness is longer than the drum length of the casting drum between the casting drums. A uniform plate may be sandwiched and the casting drum may be tightened. As a result, the slab drum is tightened while the rotation axes of the casting drum are kept parallel to each other, so that an even load can be applied to both ends of the casting drum, and the accuracy of the reduction position zero adjustment is improved. be able to. As a result, the reduction position zero point can be adjusted without including an error due to the inclination of the rotating shaft, so that the reduction position control of the cylinder can be performed accurately.
[0072]
　(Casting method of slab)
　Hereinafter, a method of casting a steel sheet by the continuous casting apparatus according to the above embodiment will be described.
[0073]
　First, before the start of casting of the slab, the pair of side dams 150d and 150w provided at the widthwise ends of the first casting drum 111 and the second casting drum 112 are opened to open the first casting drum 111 and the first casting drum 111. (2) A plate having a uniform thickness longer than the drum length of the casting drum is sandwiched between the casting drum 112 and the casting drum, and the casting drum is tightened. Then, by the above-mentioned method, the casting drum housing reduction system deformation characteristic showing the deformation characteristic of the housing supporting the casting drum and the deformation characteristic of the reduction system that reduces the casting drum is acquired. In addition to acquiring the deformation characteristics of the casting drum housing reduction system, the reduction position zero point may be adjusted.
[0074]
　Next, a control unit (not shown) that controls the continuous casting apparatus 100 calculates the plate thickness at both ends of the slab in the width direction based on the above equation 1. The continuous casting apparatus 100 is equipped with various measuring instruments such as a temperature measuring instrument for the first casting drum 111 and the second casting drum 112, and a load cell 140d and a load cell 140w for measuring the load. The control unit acquires various values ​​from these various measuring instruments and calculates the estimated plate thickness at both ends of the slab from the above equation 1. Since the control unit can use the cast drum housing reduction system deformation characteristics acquired in advance in the above equation 1, the estimated plate thickness can be calculated more accurately.
[0075]
　Next, the control unit controls the reduction positions of the cylinders provided at both ends in the width direction of the casting drum so that the calculated difference in plate thickness between both ends of the slab is equal to or less than a predetermined value. As a result, the wedges of the slabs to be cast are reduced, and as a result, meandering in the rolling mill 30 arranged downstream of the continuous casting apparatus 100 can be prevented. The calculated predetermined value of the difference in plate thickness at both ends of the slab may be empirically obtained from, for example, the meandering amount that can be tolerated in actual operation. For example, the predetermined value may be 40 μm, and more specifically, 20 μm.
[0076]
　The details of the casting method of the slab in the present embodiment have been described above.
Example
[0077]
　In this embodiment, in order to confirm the effect of the present invention, a slab was cast and rolled using the continuous casting facility 1 shown in the above embodiment. The cast drum used in this example had a drum barrel length of 1000 mm. For the cylinder position, pressure, and plate thickness, the values ​​of the stationary part were used. The evaluation of the wedge reduction effect is summarized in Table 1 below, and the absolute value of the wedge is marked as ⊚ (good) when it is less than 20 μm, ○ (pass) when it is less than 40 μm, and × (fail) when it is more than 40 μm.
[0078]
　In the first embodiment, as shown in FIG. 10, a pair of side weirs provided at the widthwise end of the casting drum is opened, and the plate thickness is uniform longer than the drum length of the casting drum between the casting drums. The reduction position zero point was adjusted with the plate sandwiched between them. In Table 1, this reduction position zero adjustment method is indicated as A. At the time of casting the slab, the reduction positions of the cylinders provided at both ends of the casting drum were controlled so that the estimated plate thicknesses at both ends of the slab were the same on the left and right sides in the width direction.
[0079]
　In Example 2, as a method of adjusting the reduction position zero point, as shown in FIG. 7, a plate shorter than the drum barrel length of the casting drum was sandwiched between a pair of casting drums to adjust the reduction position zero point. In Table 1, this reduction position zero adjustment method is indicated as B. At the time of casting the slab, the reduction positions of the cylinders provided at both ends of the casting drum were controlled so that the estimated plate thicknesses at both ends of the slab were the same on the left and right sides in the width direction.
[0080]
　In Comparative Example 1, similarly to Example 2, a plate shorter than the drum barrel length of the casting drum as shown in FIG. 7 was sandwiched between a pair of casting drums to adjust the reduction position zero point. When casting the slab, the reduction position of the cylinders provided at both ends of the casting drum was controlled so that the reduction forces at both ends of the slab drum were the same on the left and right without using the estimated plate thickness.
[0081]
　In Comparative Example 2, similarly to Example 2, a plate shorter than the drum barrel length of the casting drum as shown in FIG. 7 was sandwiched between a pair of casting drums to adjust the reduction position zero point. When casting the slab, the reduction positions of the cylinders provided at both ends of the casting drum were controlled so that the reduction positions at both ends of the slab drum were the same on the left and right without using the estimated plate thickness.
[0082]
　In the slab of Example 1, the actually measured plate thickness at the stationary portion was 1.820 mm at the end of the drive side DS and 1.830 mm at the end of the work side WS. The wedge (wedge amount) was -10 μm, which was very good. Further, even in the rolling process in the rolling mill installed downstream of the continuous casting apparatus, meandering did not occur and rolling could be carried out without any problem.
[0083]
　In the slab of Example 2, the actually measured plate thickness at the stationary portion was 1.795 mm at the end of the drive side DS and 1.828 mm at the end of the work side WS. Therefore, the wedge was −33 μm, which was good. Further, even in the rolling process in the rolling mill installed downstream of the continuous casting apparatus, meandering did not occur and rolling could be carried out without any problem.
[0084]
　In the slab of Comparative Example 1, the actually measured plate thickness at the stationary portion was 1.800 mm at the end of the drive side DS and 1.720 mm at the end of the work side WS. The wedge was as large as 80 μm, and meandering occurred in the rolling process in the rolling mill installed downstream of the continuous casting apparatus, and the slab broke.
[0085]
　In the slab of Comparative Example 2, the actually measured plate thickness at the stationary portion was 1.870 mm at the end of the drive side DS, and 1.750 mm at the end of the work side WS. The wedge was as large as 120 μm, and meandering occurred in the rolling process in the rolling mill installed downstream of the continuous casting apparatus, and the slab broke.
[0086]
[table 1]

[0087]
　From the above, in the casting of slabs by the twin-drum type continuous casting device, casting showing the deformation characteristics of the housing that supports the casting drum and the deformation characteristics of the rolling system that reduces the casting drum, which were acquired before the start of casting of the slab. Estimated plate thickness is calculated from the above equation 1 using the rolling system deformation characteristics of the drum housing, and the rolling position of the cylinder is controlled so that the difference between both ends of the slab is less than or equal to the predetermined value. It is possible to reduce the wedge of the slab well and prevent meandering in the rolling mill installed downstream of the casting drum.
[0088]
　Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.
Industrial applicability
[0089]
　The present invention has high industrial applicability because it can provide a method for casting a slab that can reduce wedges more accurately.
Code description
[0090]
　1 Continuous casting equipment
　20 1st pinch roll
　30 Roller
　31 Upper work roll
　32 Lower work roll
　33 Upper backup roll
　34 Lower backup roll
　40 2nd pinch roll
　50 Winding device
　100 Continuous casting device
　111 1st casting drum
　112 2nd casting Drum
　113 Tandish
　114 Immersion nozzle
　115 Metal molten metal pool
　116 Solidified shell
　117 Metal molten metal
　118 Thin plate
　120d, 120w Cylinder
　130d, 130w Housing
　140d, 140w Load cell
　150, 150d, 150w Side weir
　160 Test plate
　170 Roll bearing box

The scope of the claims
[Claim 1]
　Using a twin-drum type continuous casting device that solidifies molten metal with a pair of rotating casting drums to produce
　slabs, the deformation characteristics of the housing that supports the casting drums acquired before the start of casting of the slabs. Using the casting drum housing reduction system deformation characteristic showing the deformation characteristics of the reduction system that reduces the casting drum, the estimated plate thickness of both ends in the width direction of the slab is calculated from the following formula 1 and the thickness of both ends of the casting drum is calculated
　. A method for casting a slab, in which the reduction positions of cylinders provided at both ends in the width direction of the casting drum are controlled so that the difference in estimated plate thickness is equal to or less than a predetermined value.
　However, in Equation 1, the cylinder reduction position and the casting drum housing reduction system deformation represent the differences from the reduction position zero point adjustment, respectively.
　(Estimated plate thickness) = (Cylinder reduction position)
　　　　+ (Casting drum elastic deformation)
　　　　+ (Casting drum housing reduction system deformation)
　　　　+ (Casting drum drum profile)
　　　　-(Casting drum elastic deformation when adjusting the reduction position zero point ) ) ・ ・ ・ ・ ・ Equation 1
[Claim 2]
　The casting drum housing reduction system deformation characteristic is such that a pair of side dams provided at the widthwise end of the casting drum is opened, and the plate width is longer than the drum length of the casting drum and the plate thickness is between the casting drums. The method for casting a slab according to claim 1, which is obtained based on the reduction position and load of the cylinder obtained by performing tightening while sandwiching a uniform plate.
[Claim 3]
　The reduction position zero point adjustment of the casting drum is performed by opening a pair of side dams provided at the widthwise end portions of the casting drum so that the plate width is longer than the drum length of the casting drum between the casting drums. The method for casting a slab according to claim 1 or 2, wherein a plate having a uniform thickness is sandwiched between the plates.