JP6569494B2 - Thin slab manufacturing equipment and pinch roll leveling method - Google Patents

Description

  The present invention relates to a twin-drum type continuous casting apparatus and a thin-walled slab manufacturing facility provided with a pinch roll, and a pinch roll leveling method in the thin-walled slab manufacturing facility.

  When manufacturing a thin cast piece, for example, as shown in Patent Document 1, a pair of continuous casting cooling drums (hereinafter referred to as cooling drums) are arranged in parallel, and the opposing peripheral surfaces are rotated downward from above. Double-drum continuous casting, in which molten metal is poured into the hot water 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-walled slabs. A thin-walled slab manufacturing facility including an apparatus, a pinch roll, an in-line mill, and a winding device is used.

As described in Patent Document 1, the twin-drum type continuous casting apparatus solidifies and grows the molten metal poured into the hot water pool portion on the peripheral surface of the rotating cooling drum, and sends it out as a thin cast piece.
And the thin cast slab sent out from the cooling drum is sent out to a horizontal direction with a pinch roll, and is adjusted to desired plate | board thickness with a downstream in-line mill. The thin cast slab adjusted to a desired plate thickness by the in-line mill is wound up in a coil shape by a winding device installed downstream of the in-line mill.

Further, in the twin drum type continuous casting apparatus, as shown in FIG. 4 (FIG. 7 of Patent Document 1), a dummy sheet is connected to the tip of the thin cast piece, and the thin cast piece is pulled out to start casting. It is like that.
In addition, the dummy bar that leads the dummy sheet is formed to be considerably thicker than the thin-walled cast slab, and the connection portion between the tip of the thin-walled cast piece and the dummy sheet has a protrusion that is thicker than the thickness of the thin-walled cast piece. Is formed.
And rolling in an in-line mill is started after the above-mentioned projection part passes an in-line mill.

  In the twin-drum type continuous casting apparatus, the cooling drum is generally at a low temperature before the start of casting. When casting starts, the cooling drum is heated by contact with the molten metal. Further, the cooling drum is cooled from the inner surface by a cooling medium (for example, cooling water) so as not to exceed a certain temperature. The period after the temperature of the cooling drum reaches a certain level is called steady casting, and the temperature of the cooling drum during steady casting is called steady temperature.

The profile of the cooling drum changes (thermally expands) with the lapse of time from the start of casting to the time of steady casting. Therefore, the initial profile of the cooling drum has a drum diameter at the center of the cooling drum that is smaller than the end of the cooling drum so that the plate profile (plate crown) of the thin-walled slab at the time of steady casting becomes a desired plate profile. It is set to a small concave crown.
FIG. 6 is a conceptual diagram showing a change with the elapsed time after the start of casting of the profile of the cooling drum and the plate profile of the thin-walled slab when the thin-walled slab is manufactured by the conventional twin-drum type continuous casting apparatus.

  As shown in FIG. 6 (A), the cooling drum R101 at the start of casting is set to a concave profile with a concave in the center in the width direction. As a result, a thin slab S101 having a plate profile with a convex center in the width direction as shown by hatching is cast between the cooling drums R101.

      Next, after a while has elapsed from the start of casting, as shown in FIG. 6B, the cooling drum R101 expands (expands in diameter) in the center in the width direction due to heat input from the molten metal, and starts casting. Changes to R102, which is a smaller concave profile. Therefore, the plate profile of the cast strip S102 changes to a convex shape having a smaller crown amount than the cast strip S101 at the start of casting.

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

  The time required to reach FIG. 6C from FIG. 6A varies depending on the composition of the molten metal (melting temperature), the thickness of the thin-walled slab, the rotational speed of the cooling drum, and the cooling efficiency. From about 30 seconds.

On the other hand, changes in the plate profile of the thin-walled slab include not only changes due to the thermal expansion of the cooling drum, but also changes in the growth of the solidified shell due to uneven cooling of the cooling drum from the start of casting until the steady temperature is reached. .
Generally, if the cooling by the cooling drum is strong, the thickness of the solidified shell is increased, and the thickness of the thin cast slab is increased. In the width direction of the cooling drum, the cooling efficiency is higher at the end portion in the width direction of the cooling drum than in the center side in the plate direction of the cooling drum. Therefore, the thickness of the solidified shell is greater at the plate end than at the plate center. As a result, in the thin cast piece after the start of casting, the plate thickness at the plate end becomes thicker than the plate thickness at the plate center, and the portion where the plate thickness at the plate end is thick is called edge-up. This amount of edge-up is greatest at the start of casting, decreases with the elapsed time after the start of casting, and is almost eliminated during steady casting.

  FIG. 7 is a conceptual diagram showing a change in a plate profile of a thin slab caused by a change in growth of a solidified shell until the cooling drum reaches a steady temperature when a thin slab is manufactured by a twin drum type continuous casting apparatus. It is. In FIG. 7, the change of the cooling drum profile is omitted.

Immediately after the start of casting, the cooling drum width direction end is easier to escape than the cooling drum center side, so the molten metal is greatly cooled at the width direction end of the thin slab, and the solidified shell is The end in the width direction is formed thicker than the center in the width direction of the thin cast slab.
As a result, as shown in FIG. 7A, the plate profile of the thin-walled slab S201 immediately after the start of casting has a large edge-up at the end in the width direction.

After a while after the start of casting, the temperature difference between the center side of the cooling drum and the end in the width direction of the cooling drum becomes smaller than at the start of casting, and the molten metal is cooled at the end in the width direction of the thin slab more than at the start of casting. The thickness difference between the central portion and the end portion in the width direction of the solidified shell becomes smaller than that at the start of casting.
As a result, the plate profile of the thin-walled slab S202 at the time when the casting has started for a while has a smaller edge-up than the casting strip S201 immediately after the start of casting, as shown in FIG. 7B. .

After a further time has elapsed from the start of casting and the steady state has been reached, the temperature difference between the cooling drum center side and the cooling drum width direction end portion is further reduced, and the thickness of the solidified shell in the width direction center portion and end portion is reduced. The difference is almost gone.
As a result, as shown in FIG. 7C, the edge profile of the thin-walled slab S203 after the lapse of time from the start of casting has reached a steady state is almost eliminated.

  The time required to reach FIG. 7C from FIG. 7A varies depending on the composition of the molten metal (melting temperature), the thickness of the thin cast slab, the rotational speed of the cooling drum, and the cooling efficiency. It is almost the same as the case, and is about 30 seconds from the start of casting.

  From the above, the casting strip S301 from the start of casting to the time of steady casting combines the crown change due to the thermal expansion of the cooling drum and the edge-up change due to the uneven cooling of the cooling drum, as shown in FIG. Thus, immediately after the start of casting, as in S301 in FIG. 8A, when a while has elapsed after the start of casting, as in S302 in FIG. 8B, in a steady state, as in S303 in FIG. 8C. It becomes the plate profile of the cast strip.

In the thin cast slab manufacturing equipment equipped with such a twin drum type continuous casting apparatus, there are the following problems when the thin cast slab is rolled by an in-line mill.
As described above, in order to roll a thin cast slab stably and efficiently with an in-line mill, it is necessary to apply a tension to the entry / exit side of the in-line mill. A higher tension level is more effective in preventing meandering and shape defects. For this purpose, it is necessary to increase the pressing force of the pinch roll that sandwiches the thin cast piece with the pinch roll for applying the tension. When the pressing force of the pinch roll is increased, the thin cast slab may be lightly pressed. In this case, if there is an asymmetry of the elongation rate in the width direction of the thin cast slab, the pinch roll will meander.

  When meandering occurs in the pinch roll, the position of the thin cast slab on the entry side of the inline mill is off-center, and further the asymmetry of the elongation rate in the width direction of the thin cast slab in the inline mill is induced, and meandering is accelerated. . If the meandering in the in-line mill increases, the half-stretching progresses and the plate shape becomes poor, or if this half-stretching becomes large, the result is a squeezing resulting in plate breakage. There arises a problem that a plate breaks or hits a post or a guide. When the plate breaks, the subsequent thin cast piece cannot be manufactured, and the remaining molten metal is immediately discarded, so that a great yield reduction occurs.

  Further, the casting is started, and after the tip of the thin slab at the time of the steady casting passes through the inline mill, the roll gap is tightened while the roll of the inline mill is rotated, and rolling is started. This rolling method is called flying touch. If the start time of the flying touch is slow, the off-gauge becomes longer. Therefore, there is a desire to shorten the flying touch start time in the in-line mill as much as possible, that is, to apply tension more quickly with a pinch roll.

  However, when applying tension more quickly with a pinch roll, as shown in FIGS. 8A and 8B, the plate profile of the thin cast slab is thicker at the plate center and at the plate end. Even if the pressing force of the pinch roll described above is low, there are cases where only the plate center and particularly the plate end of the thin cast piece are partially rolled. At this time, if there is an asymmetry in the elongation ratio in the width direction of the thin cast slab, meandering occurs in the pinch roll, causing problems in the in-line mill described above.

  As a means for preventing meandering, for example, Patent Document 2 discloses a method for detecting the meandering amount of a thin cast piece and adjusting a gap difference between left and right in a pinch roll. Also, a method of adjusting the gap difference between the left and right of the pinch roll so as to eliminate the load difference between the left and right of the pinch roll by detecting the load on the left and right of the pinch roll, and the roll corresponding to the plate end of the thin cast slab There is a method of reducing the diameter (for example, processing into a taper shape) and reducing the influence of the concave portion of the thin cast slab (increasing the thickness of the plate end plate until steady casting) (making it difficult to be rolled).

JP 2000-343103 A Japanese Patent Laid-Open No. 2003-039108

  However, in the method of detecting the meandering amount of the thin cast slab and adjusting the gap difference between the left and right in the pinch roll, the position in the width direction of the plate is measured at two locations before and after the pinch roll to determine whether it is off-center or meandering In addition, there is a problem that high-response meandering control cannot be performed due to dead time caused by the distance between the detector for detecting the meandering amount and the pinch roll. If high-response meandering control is not possible, it will cause the above-mentioned plate breakage, which is not always sufficient.

In some cases, the thin-walled slab is not meandering, but an off-center may occur or there may be a temperature difference at both ends of the thin-walled slab. In such a case, meandering could not be suppressed by the method of adjusting the left and right gap difference in the pinch roll so as to eliminate the left and right load difference in the pinch roll. Furthermore, when the roll diameter of the portion corresponding to the plate end of the thin cast piece is reduced (for example, processed into a taper shape), the thin cast piece is not meandering, but if off-center occurs, meandering is promoted. There were drawbacks.
As described above, the conventional technique still has a problem in the meandering control in the case where there is a high response or a temperature difference (asymmetry) in the off-center or plate width direction.

  The present invention can suppress meandering of a thin-walled slab, enabling a faster flying touch. As a result, the plate breakage and off-gauge can be reduced, yield can be improved, and manufacturing cost can be reduced. It is an object of the present invention to provide a thin slab manufacturing facility and a pinch roll leveling method in the thin slab manufacturing facility.

In order to solve the above-mentioned problems, the thin-walled slab manufacturing facility according to the present invention is a twin-drum continuous slab in which a molten slab is solidified by a pair of cooling drums that are continuously poured and rotated to manufacture a thin-walled slab In a thin-walled slab manufacturing facility comprising a casting apparatus, a pinch roll that applies tension to the thin-walled slab, and an in-line mill disposed downstream of the pinch roll, the pinch roll includes the thin-walled slab A pair of rolls, and roll chocks are provided at both ends of the pair of rolls, respectively, and the pinch roll and the in-line are disposed on the roll chock at both ends of at least one of the pair of rolls. force F _L of the left and right horizontal direction (conveying direction) acting on the thin cast strip between the _mill and the load detecting unit for detecting a F _R, the inlet side of the pinch rolls and Detecting the widthwise position of the thin cast strip at one or both sides, the distance l _L from the widthwise center position of the thin cast strip to said load detecting portion of the right and _left, a position detector for detecting a l _R, measurements F _L of the load detection unit, _{F R} and the measured values l _L of said position detecting unit, from _{l R,} a moment _{M = F L × l L -F} R × acting widthwise center of the thin cast strip It is characterized by comprising: a moment calculating unit for calculating lR _; and a roll gap adjusting unit for adjusting the roll gaps at both ends of the pair of rolls so that the moment is equal to or less than a predetermined value. .

The pinch roll leveling method according to the present invention includes a twin-drum continuous casting apparatus for producing a thin slab by solidifying the molten metal with a pair of cooling drums that are continuously poured and rotated. A pinch roll leveling method in a thin-walled slab manufacturing facility comprising: a pinch roll that applies tension to a slab; and an in-line mill disposed downstream of the pinch roll, wherein the pinch roll is the thin-walled A pair of rolls sandwiching the slab is provided, and roll chocks are provided at both ends of the pair of rolls, respectively, and load detection units disposed on the roll chocks at both ends of at least one roll of the pair of rolls. , the force F _L of the left and right horizontal direction (conveying direction) acting on the thin cast strip between the said pinch rolls in-line _mill, detects the F _R Rutotomoni, wherein detecting the widthwise position of the thin cast strip at one or both of the entry side and exit side of the pinch rolls, the distance l _L from the widthwise center position of the thin cast strip to said load detecting portion of the right and left , _l detects _R, measurements F _L of the serial load detection unit, _F widthwise position of _R and the thin cast strip l _L, from _{l R,} a moment M = F acting on the widthwise center of the thin cast strip _L × l _L− F _R × l _R is calculated, and the roll gaps at both ends of the pair of rolls are respectively adjusted so that the moment becomes a predetermined value or less.

  According to the thin slab manufacturing equipment and the pinch roll leveling method of this configuration, the measurement value of the load detection unit that detects the force in the conveying direction acting on the thin slab between the pinch roll and the inline mill, Calculate the moment acting on the center of the thin cast slab in the width direction from the measurement value of the position detector that detects the position of the thin cast slab in the width direction, so that both moments of the pair of rolls are equal to or less than the predetermined value. Since the roll gap of each is adjusted, even if both ends of the thin cast piece are extended with a pinch roll, it is possible to suppress the bending of the thin cast piece being conveyed, and to suppress meandering of the thin cast piece and prevent plate breakage. be able to. Therefore, even a thin cast piece having an edge-up at the beginning of casting can be pressed with a pinch roll, and early flying touch is possible.

Here, in the pinch roll leveling method of the present invention, the roll gaps at both ends of the pair of rolls may be adjusted so that the pressing force of the entire pinch roll becomes a predetermined value.
In this case, even if the roll gaps at both ends of the pair of rolls are adjusted, the pressing force of the entire pinch roll can be set to a predetermined value, and fluctuations in the tension applied to the thin cast slab can be suppressed.

Further, in the pinch roll leveling method of the present invention, the relationship between the amount of adjustment of the roll gap at both ends of the pair of rolls and the change amount of the moment and the pressing force of the entire pinch roll is determined in advance from the start of casting. It is good also as a structure which calculates | requires for every parameter, formulates the relationship as an influence coefficient, and adjusts the roll gap of the both ends of a pair of said roll based on this influence coefficient.
As described above, the cross-sectional shape (edge-up, etc.) of the thin cast slab changes with the passage of time from the start of casting. Therefore, by calculating the adjustment amount of the roll gap at both ends of the pair of rolls using the influence coefficient obtained for each time parameter from the start of casting, it is possible to perform moment control and pressing force control with high accuracy. In addition, meandering of the thin-walled slab can be accurately suppressed.

  As described above, according to the present invention, the meandering of the thin-walled cast slab can be suppressed, so that the plate breakage can be prevented, and faster flying touch can be achieved. As a result, the off-gauge can be reduced and the yield can be improved. And the thin-walled slab manufacturing equipment which can aim at reduction of manufacturing cost, and the pinching roll leveling method in this thin-walled slab manufacturing equipment can be provided.

It is explanatory drawing which shows schematic structure of the thin slab manufacturing equipment which is embodiment of this invention. It is explanatory drawing which shows the twin drum type continuous casting apparatus, pinch roll, and in-line mill with which the thin-walled slab manufacturing equipment which is embodiment of this invention was equipped. It is a figure explaining the schematic structure of the pinch roll (1st pinch roll) which concerns on embodiment of this invention. It is a conceptual diagram explaining the outline | summary at the time of the casting start at the time of manufacturing a thin cast piece with the twin drum type continuous casting apparatus which concerns on embodiment of this invention. It is a conceptual diagram explaining the leveling method of the pinch roll in the thin slab manufacturing equipment which is embodiment of this invention. It is a conceptual diagram which shows the change with the elapsed time after the casting start of the profile of a cooling drum and the board profile of a thin walled slab at the time of manufacturing a thin walled slab by a twin drum type continuous casting apparatus. It is a conceptual diagram which shows the change of the plate profile of a thin cast piece produced by the temperature change until a cooling drum reaches steady temperature, when manufacturing a thin cast piece with a twin drum type continuous casting apparatus. It is a conceptual diagram which shows the plate profile of the thin-walled slab at the time of a casting start, when manufacturing a thin-walled slab by a twin drum type continuous casting apparatus.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a schematic configuration of a thin-walled slab manufacturing facility according to the present embodiment, and FIG. 2 is a schematic configuration diagram illustrating an example of a twin drum type continuous casting apparatus, a first pinch roll, and an inline mill. It is. Moreover, FIG. 3 is a figure explaining schematic structure of the 1st pinch roll which concerns on this embodiment.

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

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

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

The pair of cooling drums R10 includes a first cooling drum R11 and a second cooling drum R12. The first cooling drum R11 and the second cooling drum correspond to the plate thickness (internal quality) of the thin cast slab S to be manufactured. The interval of R12 can be adjusted.
The first cooling drum R11 and the second cooling drum R12 are configured such that a cooling medium (for example, cooling water) can be circulated therein and cooled by circulating the cooling medium therein. .
In this embodiment, the first cooling drum R11 and the second cooling drum R12 have, for example, an outer diameter of 800 mm and a drum body length (width) of 1500 mm. Needless to say, the outer diameter and drum length (width) of the pair of cooling drums R10 are not limited to these.

  The antioxidant 20 prevents the surface of the thin-walled slab S immediately after casting from oxidizing and generating scale. In the antioxidant 20, for example, the amount of oxygen is adjusted by nitrogen gas. It has become. It is preferable to apply the antioxidant 20 as necessary in consideration of the steel type of the thin slab S to be cast.

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

  The cooling device 30 includes, for example, a large number of spray nozzles (not shown), and in accordance with the steel type, the cooling water is ejected from the spray nozzle onto the surface (upper and lower surfaces) of the thin cast slab S to form the thin cast slab S. It is designed to cool.

As shown in FIG. 3, the first pinch roll 40 is a device that applies a pressing force to the thin cast slab S and applies a tension on the entry side of the in-line mill 50. The first pinch roll 40 has an upper pinch roll R40A and a lower pinch roll R40B, and is housed in the housing 41.
Although not shown, a spindle is connected to the upper pinch roll R40A and the lower pinch roll R40B and is driven by a motor. Further, as shown in FIGS. 3 and 5, both ends of the upper pinch roll R40A and the lower pinch roll R40B are supported by roll chocks 42A and 42B, respectively. Further, as shown in FIG. 3 and FIG. 5, on the roll exit side of the left and right roll chocks 42AR and 42AL of the upper pinch roll R40A, a horizontal direction (conveying direction) force acting on the upper pinch roll R40A is measured. A load detection device 45 is provided. Although not shown, the upper pinch roll R40A and the lower pinch roll R40B have a hollow structure and are cooled by water cooling from the inside.

  A rolling load detection device 43A is disposed above the roll chock 42A of the upper pinch roll R40A, and a pressing force applied to the thin cast slab S is detected. In addition, an electric reduction device 44 is disposed above the rolling load detection device 43A, and pass line adjustment is performed when the thin cast slab S is pressed. Furthermore, a hydraulic pressure reducing device 43B for applying a pressing force is disposed below the roll chock 42B of the lower pinch roll R40B. Although not shown, a magnescale is installed in the hydraulic pressure reducing device 43B, whereby the position of a hydraulic cylinder (not shown) in the hydraulic pressure reducing device 43B is detected, and the left and right sides of the first pinch roll 40 are detected. The roll gap amount is calculated. Although not shown, the roll chock 42A of the upper pinch roll R40A is pulled up above the housing 41 by a hydraulic device called a balancer, and when passing through the thin cast slab S, the upper pinch roll R40A and the lower pinch roll R40B. A gap is secured between them.

  In addition, position detection devices 40A and 40B for detecting the width direction position of the thin cast slab S are installed on the entry side and the exit side of the first pinch roll 40, and the first pinch roll is based on this signal. The position in the width direction of the thin slab S immediately below 40 is calculated.

In the first pinch roll 40 according to the present embodiment, the thin cast slab is calculated from the position of the thin cast S calculated by the position detectors 40A and 40B and the horizontal force measured by the load detector 45. A moment calculating section (not shown) for calculating a moment M acting on the center of S in the width direction is provided.
Then, the first pinch roll 40 of the first pinch roll 40 is moved by the hydraulic pressure reducing device 43B so that the moment M acting on the center in the width direction of the thin cast slab S obtained by the moment calculating unit becomes a predetermined value (0 in the present embodiment). The left and right roll gaps are adjusted.

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

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

  The second pinch roll 60 includes, for example, a pair of rolls that are vertically opposed to each other, a motor (motor) that drives the pinch roll, and a reduction device (hydraulic pressure) (not shown). Is reduced to generate tension between the thin cast slab S and the in-line mill 50.

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

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

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

  Next, the leveling method of the pinch roll (first pinch roll 40) according to the present embodiment will be described with reference to FIG.

In FIG. 5, (a) is a case where the plate end is rolled by the first pinch roll 40, but there is no off-center and the elongation of the plate end by the first pinch roll 40 is symmetric. Therefore, no meandering has occurred. In addition, the broken line in a figure has shown the position of the pinch roll center. Moreover, the black circle in a figure has shown the center position of the thin slab immediately under a pinch roll. In this case, left and right roll chock 42AL, horizontal force of right and left provided on 42AR _F L, the load detecting apparatus 45L for detecting an _{F R,} is under the same pressure on the 45R. Further, the center position in the width direction of the thin slab S immediately below the first pinch roll 40 from the position detection devices 40A and 40B provided before and after the first pinch roll 40 coincides with the position of the center of the pinch roll. Thin slab horizontal force from the width direction center position of the left and right S _F L, the load detecting apparatus 45L for detecting an _{F R,} the distance _l L, _{l R} to 45R are the same distance. At this time, the moment M = F _L × l _L −F _R × l _R acting on the center of the thin cast slab is zero, and the roll gap of the first pinch roll 40 does not need to be corrected.

In FIG. 5, (b) shows a case where the plate end is rolled by the first pinch roll 40 and there is an off-center, but the elongation of the plate end by the first pinch roll 40 is symmetric. Therefore, no meandering has occurred. In addition, the broken line in a figure has shown the position of the pinch roll center. Moreover, the black circle in a figure has shown the center position of the thin slab immediately under a pinch roll. In this case, the right and left roll chocks 42AL, horizontal force of the right and left provided on 42AR _F L, the load detecting apparatus 45L for detecting an _{F R,} 45R is the force of off-center side (the thin cast strip is closer side) Is bigger. Further, the center position in the width direction of the thin cast piece S immediately below the first pinch roll 40 from the position detection devices 40A and 40B provided before and after the first pinch roll 40 does not coincide with the position of the center of the pinch roll. Horizontal force of the left and right from the widthwise center position of the thin slab S _F L, the load detecting apparatus 45L for detecting an _{F R,} the distance to 45R _l L, _{l R} are different, in FIG. 6 (b), _{l R} > L _L. At this time, the moment M = F _L × l _L −F _R × l _R acting on the center in the width direction of the thin cast slab S is zero, and the roll gap of the first pinch roll 40 does not need to be corrected.

In FIG. 5, (c) shows a case where the plate end is rolled by the first pinch roll 40 but there is no off-center, but the elongation of the plate end by the first pinch roll 40 is asymmetric. Therefore, meandering has occurred. In this case, as shown in the drawing, a camber (bend) is generated at an initial stage, resulting in meandering. When the meandering further proceeds, problems such as shape defects, camber, and plate breakage due to drawing are caused when rolling in the in-line mill 50 downstream of the first pinch roll 40.
In addition, the broken line in a figure has shown the position of the pinch roll center. Moreover, the black circle in a figure has shown the center position of the thin slab immediately under a pinch roll. In this case, the right and left roll chocks 42AL, horizontal force _F L of the right and left provided on 42AR, load detection apparatus for detecting _{F R} 45L, the 45R, becomes because the tension of more extended the plate end portion smaller As a result, is smaller than F _R horizontal force F _L of the more extended the side. Further, the center position in the width direction of the thin slab S immediately below the first pinch roll 40 from the position detection devices 40A and 40B provided before and after the first pinch roll 40 coincides with the position of the center of the pinch roll. Thin slab horizontal force from the width direction center position of the left and right S _F L, the load detecting apparatus 45L for detecting an _{F R,} the distance _l L, _{l R} to 45R are the same distance. At this time, the moment M = F _L × l _L −F _R × l _R acting on the center in the width direction of the thin cast slab S is not zero, and the roll gap of the first pinch roll 40 needs to be corrected.

  Although three patterns have been described in FIG. 5, it is possible to suppress meandering of the thin cast slab S by performing the moment control also for other patterns (for example, when off-center and camber occur simultaneously). confirmed.

Next, a method for controlling the roll gap of the first pinch roll 40 to make the moment M described above zero will be described.
When the left and right roll gaps of the first pinch roll 40 are adjusted to control the moment M acting on the center in the width direction of the thin cast slab S, the pressing force P of the entire first pinch roll 40 also changes. Become.

Therefore, an experiment is performed in advance to obtain a moment change amount ΔM and a pressing force change amount ΔP with respect to the left and right independent roll gap adjustment amounts (ΔG _R , ΔG _L ) of the first pinch roll, and an influence coefficient α of the following equation (1) ₁ , α ₂ , α ₃ , α ₄ are calculated.

この（２）式において、薄肉鋳片の幅方向中央に作用するモーメントＭが零となるように、ΔＭを入力することで、第１ピンチロール４０の左右のロールギャップ調整量（ΔＧ_Ｒ，ΔＧ_Ｌ）を求めることができる。 Next, the following equation (2) can be obtained by taking the inverse matrix of the equation (1).

In this equation (2), the right and left roll gap adjustment amounts (ΔG _R , ΔG) of the first pinch roll 40 are input by inputting ΔM so that the moment M acting on the center in the width direction of the thin cast slab becomes zero. _L ) can be obtained.

Here, when it is desired to keep the pressing force P in the entire first pinch roll 40 constant when the roll gap is adjusted, ΔP _ref = 0 in this equation (2).
Here, the reason why the pressing force P of the first pinch roll 40 is not changed is that when the pressing force P of the pinch roll is changed, the tension between the first pinch roll 40 and the inline mill 50 varies, and This is because it induces plate thickness variation and shape variation. Moreover, when changing the peripheral speed of the 1st pinch roll 40 so that the tension | tensile_strength between the 1st pinch roll 40 and the inline mill 50 may not be changed, the speed of the inline mill 50 is also cast speed (casting start time is short) in connection with it. In this example, it is necessary to control in consideration of the casting speed rising within 30 seconds after the start of casting), and the control system becomes complicated, because the response speed of the speed system is slower than the reduction system. is there.

Further, as described above, the plate profile (plate crown and plate temperature) of the thin-walled slab S changes depending on the time from the start of casting. Therefore, the same roll gap adjustment amount (ΔG _R , ΔG depends on the time from the start of casting. _L ), and the moment variation ΔM described above is different.
Although it may be possible by calculation, an experiment is actually performed in advance here, and the influence coefficient is obtained every time from the start of the casting time.
At a certain time (t) from the start of casting, a moment change amount ΔM and a pressing force change amount ΔP with respect to the left and right independent roll gap adjustment amounts (ΔG _R , ΔG _L ) of the first pinch roll 40 are obtained. Thereby, the influence coefficients α ₁ (t), α ₂ (t), α ₃ (t), and α ₄ (t) of the following equation (3) are obtained. That is, the influence coefficient is obtained as a function of time.

この（４）式から、時刻(ｔ）における薄肉鋳片Ｓの板プロフィルが変化した場合でも、押付力Ｐを変化させず、モーメントＭを零とする第１ピンチロール４０のロールギャップ調整量（△Ｇ_Ｒ、ΔＧ_Ｌ）が求まる。 Next, the following equation (4) can be obtained by taking the inverse matrix of the equation (3).

From this equation (4), even when the plate profile of the thin cast slab S changes at time (t), the roll gap adjustment amount of the first pinch roll 40 (the moment M is zero without changing the pressing force P) ( ΔG _R , ΔG _L ) is obtained.

As described above, according to the present embodiment, the right and left roll chocks 42AL, horizontal force of the right and left provided on 42AR _F L, the load detecting apparatus 45L for detecting an _{F R,} and the measurement value of 45R, the first pinch roll 40 before and after The moment M acting on the center in the width direction of the thin slab S is calculated from the center position in the width direction of the thin slab S immediately below the first pinch roll 40 detected by the position detection devices 40A and 40B provided in the Since the left and right roll gaps of the first pinch roll 40 are adjusted so that M is equal to or less than a predetermined value (zero in this embodiment), both ends of the thin cast slab S are covered with the first pinch roll 40. Even when pressed so as to extend, it is possible to suppress bending of the thin cast slab S, and to suppress meandering of the thin cast slab S. Therefore, even if it is the thin slab S having the edge-up at the initial stage of casting, the thin slab S can be sandwiched by the first pinch roll 40 with a predetermined pressing force, and early flying touch is possible.

Further, in the present embodiment, by setting ΔP _ref = 0 in Expression (2) and Expression (4), the entire first pinch roll 40 is adjusted even if the left and right roll gaps of the first pinch roll 40 are adjusted. Therefore, it is possible to prevent the tension applied to the thin-walled slab S from fluctuating.
Furthermore, in this embodiment, by calculating | requiring an influence coefficient as a function of time in Formula (4), according to the cross-sectional shape (edge up etc.) of the thin slab S, appropriate roll gap adjustment amount ((DELTA) G) _R , ΔG _L ) can be set, and moment control and pressing force control can be performed with high accuracy.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.
For example, in the present embodiment, the dummy sheet is used at the start of casting. However, the present invention is not limited to this, and the present invention may be applied to a twin-drum continuous casting apparatus having another configuration.

  In the present embodiment, the load detection device is provided on the roll chock of the upper pinch roll. However, the present invention is not limited to this, and the load detection device may be provided on the roll chock of the lower pinch roll. Alternatively, a load detection device may be provided on each of the upper pinch roll and the lower pinch roll.

Next, experimental results confirming the effects of the present invention will be described.
The equipment used in this experiment is the same as that shown in FIG. The thin cast slab is steel with a plate thickness of 2 mm and a plate width of 1200 mm. The cooling drum acceleration rate from the start of casting is 150 m / min / 30 seconds, and the cooling drum rotation speed in the steady casting state is 150 m / min. At that time, rolling with a reduction rate of 30% is performed in an in-line mill, and the thickness of the in-line mill exit side is 1.4 mm. The tension between the first pinch roll and the in-line mill is 3.6 tf (stress: about 15 MPa) as a resultant force. The pressing force is about 15 tf in total on the left and right.

  As Conventional Example 1, load control was performed so that the pressing force of the first pinch roll was constant (right 7.5 tf, left 7.5 f).

  As an example of the present invention, the left and right roll gaps of the pinch roll are set so as to have a pressing force (right 7.5 tf, left 7.5 f) set in advance by the first pinch roll in a condition without off-center. For each time parameter from the start of casting, the relationship between the amount of change in the roll gap and the amount of change in the horizontal moment acting on the pinch roll when the left and right roll gaps are changed while controlling Further, the position of the thin cast slab is detected on the entry / exit side of the first pinch roll, the position of the thin cast slab immediately below the first pinch roll is calculated based on the value, and further the load detection device of the first pinch roll A calculator for calculating a horizontal moment acting on the first pinch roll based on a signal in the horizontal direction and a signal of the position of the thin thin slab, and a module in the horizontal direction based on the calculation result. When the left and right roll gap reduction devices of the first pinch roll are controlled so that the tension becomes zero, even if the left and right roll gaps of the pinch roll change, the vertical pressing force of the pinch roll is The left and right roll gaps of the pinch rolls were controlled so as to have a set pressing force (15tf in the resultant force).

Example 1
In Conventional Example 1, Conventional Example 2, and Invention Example, the position of the thin cast slab (off center amount) was intentionally changed using a guide roll (off center amount: 0 mm to 50 mm), and the meandering situation was examined.
In Conventional Example 1, when there was an off-center, the meandering was promoted, and finally, the thin cast piece hit the first housing post, and the plate broke.
In Conventional Example 2 and the present invention example, meandering was prevented even when there was an off-center, and the plate did not break. In the example of the present invention, the left and right horizontal loads fluctuated in the range of 6 to 7 tf / 8 to 9 tf, respectively, and maintained 15 tf as a whole.

(Example 2)
In the conventional example 1 and the present invention example, the thin cast slab is non-uniformly cooled in the plate width direction upstream of the first pinch roll to give an asymmetry of temperature distribution (about 80 ° C.), and the position of the thin cast slab (off-center) -Amount) was intentionally changed using a guide roll (off-center amount: 0 mm to 50 mm), and the meandering state was examined. As a result, when the conventional example 1 has an asymmetry of the temperature distribution, the meandering was promoted, and finally the thin cast piece hit the first housing post, and the plate broke. In addition, when there was an off-center, the thin cast piece hit the first housing post in a shorter time, and the plate broke.
In the present invention example, meandering was prevented even when there was an asymmetry in temperature distribution and there was off-center, and the plate did not break. In the example of the present invention, the left and right horizontal loads fluctuated in the range of 6 to 7 tf / 8 to 9 tf, respectively, but maintained 15 tf as a whole.

  Further, if the pressing force with the pinch roll cannot be secured, the tension in the rolling cannot be secured, the plate shape becomes poor and the plate breaks. Therefore, the time from the start of the flying touch to the completion (reduction until the desired thickness is reached) is important. This effect was investigated in the same manner as in Example 1 except for off-center 50 mm and no temperature distribution. Conventionally, flying touch was not possible until the thin-walled slab reached a steady state (about 28 seconds from casting start, about 40 m off-gauge). However, in the present invention, since it does not meander even when a pressing force is applied, a flying touch is applied before the thin cast slab reaches a steady state (about 14 seconds from the start of casting, about 20 meters off gauge). The start was completed.

  From the above, according to the present invention, in the thin slab manufacturing equipment equipped with the twin drum type continuous casting apparatus, meandering with a pinch roll can be prevented, and the thin slab can be stably manufactured, and It has been clarified that the off-gauge can be reduced because the praying touch can be accelerated, and as a result, the manufacturing cost can be reduced.

  According to the thin slab manufacturing equipment and the pinch roll leveling method according to the present invention, it is possible to reduce the off-gauge and improve the yield of the thin slab by reducing the time to the flying touch. Is available.

S thin cast slab 1 thin cast slab manufacturing equipment 10 twin drum type continuous casting device 40 first pinch rolls 40A, 40B position detection device (position detection unit)
42A, 42B Roll chock 43B Hydraulic reduction device (roll gap adjusting part)
45 (45L, 45R) Load detector (load detector)
50 inline mill

Claims (4)

A twin-drum continuous casting apparatus for producing a thin cast piece by solidifying the molten metal with a pair of rotating drums that continuously inject and rotate the molten metal, a pinch roll that applies tension to the thin cast piece, and the pinch In a thin slab manufacturing facility provided with an in-line mill arranged on the downstream side of the roll,
The pinch roll has a pair of rolls for sandwiching the thin cast piece, and roll chocks are provided at both ends of the pair of rolls,
Is disposed on the roll chocks of the ends of at least one roll of the pair of rolls, the force F _L of the left and right horizontal direction (conveying direction) acting on the thin cast strip between the said pinch rolls in-line _mill, a F _R A load detection unit to detect;
The width direction position of the thin cast piece on one or both of the entrance side and the exit side of the pinch roll is detected, and the distances l _L and l _R from the center position in the width direction of the thin cast piece to the left and right load detection units A position detection unit for detecting
Measurements F _L of the load detection unit, _{F R} and the measured values l _L of said position detecting unit, from _{l R,} a moment _{M = F L × l L -F} R × acting widthwise center of the thin cast strip a moment calculation unit for calculating lR _;
A roll gap adjusting unit that adjusts the roll gaps at both ends of the pair of rolls so that the moment is equal to or less than a predetermined value;
A thin-walled slab manufacturing facility characterized by comprising: A twin-drum continuous casting apparatus for producing a thin cast piece by solidifying the molten metal with a pair of rotating drums that continuously inject and rotate the molten metal, a pinch roll that applies tension to the thin cast piece, and the pinch A pinch roll leveling method in a thin-walled slab manufacturing facility comprising an in-line mill disposed on the downstream side of the roll,
The pinch roll has a pair of rolls for sandwiching the thin cast piece, and roll chocks are provided at both ends of the pair of rolls,
Left and right horizontal (conveying direction) force F acting on the thin cast slab between the pinch roll and the in-line mill by load detecting portions disposed on the roll chock at both ends of at least one of the pair of rolls. _L, detects the _{F R,}
The width direction position of the thin cast piece on one or both of the entrance side and the exit side of the pinch roll is detected, and the distances l _L and l _R from the center position in the width direction of the thin cast piece to the left and right load detection units Detect
Measurements F _L of the serial load detection unit, _F widthwise position of _R and the thin cast strip l _{L, l} from _R, the thin cast strip width direction central moment M = _{F L} × _{l L} -F acts on _R of Xl _R is calculated,
A pinch roll leveling method, wherein the roll gaps at both ends of the pair of rolls are adjusted so that the moment is equal to or less than a predetermined value.   The leveling method of the pinch roll according to claim 2, wherein a roll gap at both ends of the pair of rolls is adjusted so that a pressing force of the entire pinch roll becomes a predetermined value.   The relationship between the adjustment amount of the roll gap at both ends of the pair of rolls, the moment, and the amount of change in the pressing force of the entire pinch roll is obtained for each time parameter from the start of casting, and the relationship is expressed as an influence coefficient. 4. The pinch roll leveling method according to claim 2, wherein a roll gap at both ends of the pair of rolls is adjusted based on the influence coefficient.

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