Slab warpage detection apparatus and method of detecting warpage of slab

Abstract

Provided is a slab warpage detection apparatus detecting warpage of a slab drawn from a mold in continuous casting equipment. The slab warpage detection apparatus includes a pair of pressing roils that pinches the slab on a rear side of a roll segment, supporting the slab drawn from the mold, in a slab drawing direction, a movement unit that supports the pair of pressing rolls to be movable in a thickness direction of the slab, and a position detecting unit that detects positions of the pressing rolls in the thickness direction of the slab.

Claims

1. A slab warpage detection apparatus detecting warpage of a slab drawn from a mold in continuous casting equipment, the slab warpage detection apparatus comprising: a pair of pressing rolls that pinches the slab on an exit side of a roll segment supporting the slab drawn from the mold; a pair of movement units, each movement unit of the pair of movement units configured to support a respective pressing roll of the pair of pressing rolls, each of the pressing rolls of the pair of pressing rolls configured to be movable in a thickness direction of the slab; a position detecting unit that detects positions of each of the pressing rolls in the thickness direction of the slab; and a control device programmed to: receive information of the position of each of the pressing rolls detected by the position detecting unit; determine whether an amount of displacement of the positions of each of the pressing rolls in the thickness direction of the slab exceeds a predetermined value; and adjust pressing forces of the pair of pressing rolls to straighten warpage of the slab in a case where the amount of displacement of the positions of the pressing rolls in the thickness direction of the slab exceeds the predetermined value; wherein the movement unit comprises a cylinder and a rod portion disposed to be retractable from the cylinder, and the pressing rolls are provided at a tip of the rod portion, wherein the position detecting unit is connected to the control device, and wherein the warpage of the slab is straightened by generating a difference between pressing forces of the respective pressing roll of the pair of pressing rolls and applying a bending deformation to the slab.

2. The slab warpage detection apparatus according to claim 1, wherein the slab having a center solid phase ratio of 70% or higher is used as a detection target.

3. The slab warpage detection apparatus according to claim 1, wherein the continuous casting equipment is vertical-type continuous casting equipment.

4. A method of detecting warpage of the slab using the slab warpage detection apparatus according to claim 1, the method comprising: detecting warpage of a slab by causing the position detecting unit to detect the positions of the pressing rolls when the pair of pressing rolls moves in the thickness direction of the slab in a manner following a shape of the slab in a state where the slab is pinched by the pair of pressing rolls; and straightening warpage of the slab by adjusting pressing forces of the pair of pressing rolls in a case where an amount of displacement of the positions of the pressing rolls in the thickness direction of the slab exceeds a predetermined value.

5. The slab warpage detection apparatus according to claim 2, wherein the continuous casting equipment is vertical-type continuous casting equipment.

6. A method of detecting warpage of the slab using the slab warpage detection apparatus according to claim 2, the method comprising: detecting warpage of a slab by causing the position detecting unit to detect the positions of the pressing rolls when the pair of pressing rolls moves in the thickness direction of the slab in a manner following a shape of the slab in a state where the slab is pinched by the pair of pressing rolls; and straightening warpage of the slab by adjusting pressing forces of the pair of pressing rolls in a case where an amount of displacement of the positions of the pressing rolls in the thickness direction of the slab exceeds a predetermined value.

7. A method of detecting warpage of the slab using the slab warpage detection apparatus according to claim 3, the method comprising: detecting warpage of a slab by causing the position detecting unit to detect the positions of the pressing rolls when the pair of pressing rolls moves in the thickness direction of the slab in a manner following a shape of the slab in a state where the slab is pinched by the pair of pressing rolls; and straightening warpage of the slab by adjusting pressing forces of the pair of pressing rolls in a case where an amount of displacement of the positions of the pressing rolls in the thickness direction of the slab exceeds a predetermined value.

8. A method of detecting warpage of the slab using the slab warpage detection apparatus according to claim 5, the method comprising: detecting warpage of a slab by causing the position detecting unit to detect the positions of the pressing rolls when the pair of pressing rolls moves in the thickness direction of the slab in a manner following a shape of the slab in a state where the slab is pinched by the pair of pressing rolls; and straightening warpage of the slab by adjusting pressing forces of the pair of pressing rolls in a case where an amount of displacement of the positions of the pressing rolls in the thickness direction of the slab exceeds a predetermined value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view describing continuous easting equipment in which a slab warpage detection apparatus and a method of detecting slab warpage according to an embodiment of the present invention is applied.

(2) FIG. 2 is a side view for describing a schematic configuration of the slab warpage detection apparatus described above.

(3) FIG. 3 is a plan view of the same slab warpage detection apparatus.

(4) FIG. 4 is a side view illustrating a method of calculating a warpage amount in the same slab warpage detection apparatus.

(5) FIG. 5 is a side view illustrating a method of straightening warpage of a slab in the same slab warpage detection apparatus.

(6) FIG. 6 is a side view for describing a schematic configuration of a slab warpage detection apparatus according to another embodiment of the present invention.

(7) FIG. 7 is a side view for describing a schematic configuration of a slab warpage detection apparatus according to still another embodiment of the present invention.

EMBODIMENTS OF THE INVENTION

(8) Hereinafter, a slab warpage detection apparatus and a method of detecting slab warpage according to embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to only the following embodiments.

(9) First continuous easting equipment 10 in which a slab warpage detection apparatus 20 and a method of detecting slab warpage according to the present embodiment are applied will be described.

(10) The continuous casting equipment 10 illustrated in FIG. 1 is a vertical-type continuous casting machine including a mold 11, a roll segment 13 that is disposed in a plurality of stages below this mold 11 and supports a slab 1 drawn from the mold 11, cutters 15 that cut the slab 1, and a lower conveying rolls 17 that support and convey the slab 1 on a side below the cutters 15.

(11) In the present embodiment an example in which the slab 1 is pressed and pinched by a pair of pressing rolls 21 with pressing forces equal to each other is described. However, the pressing roils 21 may be in a state of being is contact with the slab 1.

(12) Then, the slab warpage detection apparatus 20 according to the present embodiment is provided between the roll segment 13 and the cutters 15. As illustrated in FIG. 1, it is preferable that the slab warpage detection apparatus 20 is provided immediately below the roll segment 13 (on an upstream side of a different apparatus located on a downstream side of the roll segment 13 in a direction in which a slab is conveyed). That is, before going through a different step (before the slab 1 is conveyed to a different apparatus), it is preferable that the slab warpage detection apparatus 20 detects warpage of the slab 1 cooled in the roll segment 13. In such a configuration, warpage of the slab 1 can be sensed in an early stage, and a warpage amount thereof can be measured.

(13) As illustrated in FIGS. 2 and 3, this slab warpage detection apparatus 20 includes the pair of pressing rolls 21 (21A and 21B) that presses and pinches the slab 1, movement units 24 that respectively support the pressing rolls 21 to be movable in a pressing direction F of the slab 1, and position detecting units 28 that detect positions of the pressing rolls 21 in the pressing direction F.

(14) In the present embodiment, as illustrated in FIG. 2, the pair of pressing rolls 21 (21A and 21B) pinching the slab 1 in its sheet thickness direction is provided in two stages in a drawing direction of the slab 1.

(15) In addition, the movement unit 24 supporting the pressing roll 21 includes a cylinder 25 fixed to a frame 29, and a rod portion 26 disposed to be retractable in a horizontal direction from this cylinder 25. The pressing roll 21 is provided at a tip of the rod portion 26. In the present embodiment, as illustrated in FIGS. 2 and 3, the movement units 24 are constituted of eight cylinders 23 respectively basing the rod portions 26. Then, one pressing roll 21 is provided with respect to the tips of the pair of rod portions 26. Therefore, in the present embodiment, four pressing rolls 21 are supported by four pairs of rod portions 26.

(16) The position detecting unit 28 is installed in the rod portion 26 of each of the cylinders 25 and detects the position of the pressing roll 21, provided at the tip of each of the rod portions 26, in the pressing direction F. As illustrated in FIG. 1, each of position detecting units 28 is connected to a control device 30, and information of the positions of the pressing rolls 21 in the pressing direction F detected by these position detecting units 28 are transmitted to the control device 30.

(17) Next, a method of detecting warpage of a slab using the slab warpage detection apparatus 20 according to the present embodiment will be described.

(18) The slab 1 drawn from the mold 11 is fixed and supported by the roll segment 13 and is drawn downward in a vertical direction. A cooling unit is provided in the roll segment 13. Here, the slab 1 is cooled by the cooling unit provided in the roll segment 13. In an exit part of the roll segment 13, solidification has progressed to the extent that the slab 1 does not expand due to static pressure. Generally, a center solid phase ratio is 70% or higher.

(19) In addition, since the slab 1 is fixed and supported by the roll segment 13, even in a case where cooling is not uniformly performed, warpage of the slab 1 is not manifested. At the point of time the slab 1 comes out of the roll segment 13, the slab 1 can be deformed in a relatively free manner, and warpage is manifested.

(20) The slab warpage detection apparatus 20 according to the present embodiment may be provided between the roll segment 13 and the cutters 15 for cutting the slab 1 in the continuous casting equipment 10. In this case, particularly, in the continuous easting equipment 10 in which the slab 1 is drawn downward in the vertical direction and the slab 1 is cut into predetermined lengths by the cutters 15, it is possible to prevent the slab 1 from riding on conveying rolls 17 which pinch and support the slab 1 on a downstream side of the cutters 15, to prevent the slab 1 from being not able to be supported any longer, and to prevent an operation from stopping.

(21) In the slab warpage detection apparatus 20 according to the present embodiment, on the exit side of the roll segment 13, the slab 1 is in a state of being pressed by the pair of pressing rolls 21 (21A and 21B) in a thickness direction of the slab 1 with pressing forces equal to each other. In a case where the slab 1 is pressed by the pair of pressing rolls 21 (21A and 21B) with pressing forces equal to each other, there is no need for each of the pressing forces in the horizontal direction to strictly coincide with each other. A difference may be present between pressing forces to the extent that the slab 1 is not deformed. An allowable difference between pressing forces varies due to the material, the cross-sectional shape, and the like of a slab. It is preferable that the allowable difference is 20 t or lower.

(22) In this state, in a case where warpage is generated in the slab 1, the pressing rolls 21 move along the pressing direction F in a manner following the shape of the slab 1. In FIG. 4, as indicated with two-dot chained line, the pressing rolls 21 move to the right side. These positions of the pressing rolls 21 are detected by the position detecting units 28 installed in the rod portions 26 of the cylinders 25. Then, information of the positions of the pressing rolls 21 in the pressing direction F is transmitted from the position detecting units 28 to the control device 30.

(23) In the control device 30, from information of the positions of the pressing rolls 21 detected by the position detecting units 28, an amount of displacement of the positions of the pressing rolls 21 on the upper side in the thickness direction of the slab 1 and an amount of displacement of the positions of the pressing rolls 21 on the lower side in the thickness direction of the slab 1 are calculated. Then, in addition to a distance A between the pressing rolls 21 on the upper side and the pressing rolls 21 on the lower side, and a distance B between the pressing rolls 21 on the lower side and the lower conveying rolls 17 which are set in advance, an amount C of displacement of the positions of the pressing rolls 21 on the lower side and an amount D of displacement of the positions of the pressing rolls 21 on the upper side are calculated. A warpage amount X in parts of the lower conveying rolls 17 is calculated by the following (Expression 1). For example, the unit of mm can be used as each of the variables,
X=(C−D)×B/A+C   (Expression 1)

(24) If this warpage amount X exceeds a predetermined value, there is concern that the slab 1 rides on the lower conveying rolls 17, so that conveyance of the slab 1 has to be stopped. Therefore, at the point of time the slab 1 comes out of the roll segment 13, there is a need to straighten warpage of the slab 1 as necessary by sensing warpage of the slab 1 based on information of the positions of the pressing rolls 21.

(25) In the present embodiment, as illustrated in FIG. 5, warpage is straightened by adjusting pressing forces of the pressing rolls 21 (21A and 21B) and causing the slab 1 to be subjected to bending deformation. That is, warpage of the slab 1 is straightened by generating a difference between pressing forces of the pressing rolls 21A on one side and pressing forces of the pressing rolls 21B or the other side and applying bending deformation to the slab 1, in the pair of pressing rolls 21 (21A and 21B) pinching the slab 1.

(26) In the present embodiment, as illustrated in FIG. 5, warpage is straightened by causing the pair of pressing rolls 21 (21A and 21B) on the upper side and the pair of pressing rolls 21 (21A and 21B) on the lower side to be relatively move in the opposite directions and causing the slab 1 to be subjected to bending deformation.

(27) According to the slab warpage detection apparatus 20 and the method of detecting slab warpage according to the present embodiment having a configuration as described above, the slab warpage detection apparatus 20 includes the pair of pressing rolls 21 (21A and 21B) that presses and pinches the slab 1, the movement units 24 that support these pressing rolls 21 to be movable in the pressing direction F, and the position defecting units 28 that defect the positions of the pressing rolls 21 in the pressing direction F. Therefore, in a state where the slab 1 is pressed by the pair of pressing rolls 21 (21A and 21B) with pressing forces equal to each other, warpage of the slab 1 can be sensed by causing the position detecting units 28 to detect the positions of the pressing rolls 21 when the pressing rolls 21 move in the pressing direction F in a manner following the shape of the slab 1.

(28) In addition, the pair of pressing rolls 21 (21A and 21B) is provided at the exit part of the roll segment 13 fixing and supporting the slab 1 drawn from the mold 11. Therefore, at the point of time warpage is manifested, warpage of the slab 1 can be sensed in an early stage, so that the warpage amount can be accurately measured.

(29) Moreover, in the present embodiment, as illustrated in FIG. 4, the warpage amount X of the positions of the lower conveying rolls 17 can be estimated from the amount of displacement of the positions of the pair of pressing rolls 21 (21A and 21B) in the pressing direction F provided at the exit part of the roll segment 13. Thus, before the slab 1 arrives at the lower conveying rolls 17, the slab 1 can be prevented from riding on the lower conveying rolls 17 by straightening warpage, so that an operation can be stably performed.

(30) In addition, in the present embodiment, a case where two sets of the pair of pressing rolls 21 (21A and 21B) are vertically provided is illustrated. In the case of such a form, warpage of the slab 1 can be sensed from a difference between the amount of displacement of the positions of the pressing rolls 21 on the upper side in the pressing direction F and the amount of displacement of the positions of the pressing rolls 21 on the lower side in the pressing direction F.

(31) Moreover, when warpage of the slab 1 is straightened, warpage of the slab 1 can be straightened in a relatively simple manner by causing the pair of pressing rolls 21 (21A and 21B) on the tipper side and the pair of pressing rolls 21 (21A and 21B) on the lower side to move in directions opposite to each other by applying bending deformation to the slab 1.

(32) Hereinabove, the slab warpage detection apparatus and the method of detecting slab warpage according to the embodiment of the present invention have been described. However, the present invention is not limited to only the forms described above, and suitable changes can be made within a range not departing from the technical ideas of the invention.

(33) For example, in the description of the present embodiment as illustrated, in FIG. 2, the movement units supporting the pair of pressing rolls 21 (21A and 21B) on the upper side and the movement units supporting the pair of pressing rolls 2 (21A and 21B) on the lower side are fixed to the same frame 29. However, the embodiment is not limited thereto. As illustrated in FIG. 6, the movement units 24 supporting the pair of pressing rolls 21 (21A and 21B) on the upper side and the movement units 24 supporting the pair of pressing rolls 21 (21A and 21B) on the lower side may be fixed to the frames 29 different from each other.

(34) Moreover, in the description of the present embodiment, two sets of the pair of pressing rolls are provided. However, the embodiment is not limited thereto. As illustrated in FIG. 7, one set of the pair of pressing rolls 21 (21A and 21B) may be provided. Even in this case, the warpage amount of the slab 1 can be measured from a distance between a pinching roll 14 and the pressing rolls 21 constituting the roll segment 13, and the amount of displacement of the positions of the pair of pressing rolls 21 (21A and 21B) in the pressing direction F. For example, as illustrated in FIG. 7, in a case where a distance between the pinching roll 14 of the lowermost portion and the pressing rolls 21 is A′, a distance between the pressing rolls 21 and the lower conveying rolls 17 is B′, and the amount of displacement of the positions of the pressing rolls 21 in a pressing direction is E in a plurality of pinching rolls 14 constituting the roll segment 13, similar to the case described above, the warpage amount X can be calculated by the following (Expression 2). For example, the unit of mm can be used as each of the variables.
X=E×B′/A′+E   (Expression 2)

(35) In addition, in the description of the present embodiment, the position detecting units 28 are provided in the movement units 24 on both sides of the pair of pressing rolls 21 (21A and 21B). However, the embodiment is not limited thereto. The position detecting unit 28 may be provided on only the movement unit 24 on one side.

(36) In addition, in the description of the present, embodiment, the movement unit 24 has a cylinder structure. However, the embodiment is not limited thereto. For example, the movement unit 24 may move a mechanical screw using an electric motor.

(37) In addition, in the description of the present embodiment the pressing rolls 21 (21A and 21B) are configured to straighten warpage of the slab 1. However, the embodiment is not limited thereto. There is no limitation for the method of straightening warpage. For example, cooling may be performed on only one surface of the slab 1. When cooling is performed on only one surface of the slab 1, a temperature difference is generated in the thickness direction of the slab 1 so that the slab 1 is deformed. Warpage of the slab 1 can be straightened by utilizing this deformation. It is preferable that a cooling device for the slab 1 is provided immediately below the slab warpage detection apparatus 20 according to the present embodiment.

(38) In the present embodiment, the slab 1 having a thickness of 50 mm or greater in a cross section perpendicular to the drawing direction of the slab 1 is preferably used. In a case where the slab 1 satisfies this condition, a problem of warpage of the slab 1 is manifested, and the slab warpage detection apparatus 20 according to the present embodiment is preferably used. The cross-sectional shape of the slab 1 may be a rectangular shape, a circular shape, an elliptic shape, an H-shape or the like.

(39) As in the continuous casting equipment 10 according to the present embodiment, the slab warpage detection apparatus 20 is provided between the roll segment 13 and the cutters 15. Therefore, particularly, before the slab 1 is drawn downward in the vertical direction and the slab 1 is cut into predetermined lengths by the cutters 15, it is possible to prevent the slab 1 from riding on the conveying rolls 17 which support a slab on a side below the cutters 15, to prevent the slab 1 from being not able to be supported any longer, and to prevent an operation from stopping.

(40) In addition, the continuous casting equipment 10 according to another embodiment of the present invention includes the mold 11, the roll segment 13 that is disposed in a plurality of stages below this mold 11 and supports the slab 1 drawn from the mold 11, and the slab warpage detection apparatus 20 that detects warpage of the slab 1 drawn from the mold 11. The continuous casting equipment 10 includes the slab warpage detection apparatus 20 that has the pair of pressing rolls 21 pinching the slab 1 on the exit side of the roll segment 13, the movement units 24 supporting this pair of pressing rolls 21 to be movable in the thickness direction of the slab 1, and the position detecting units 28 detecting the positions of the pressing rolls 21 in the thickness direction of the slab; the cutters 15 that cut the slab 1; and the lower conveying rolls 17 that support and convey the stab 1 on a side below the cutters 15.

(41) In addition, the method according to still another embodiment of the present invention is a method including detecting of warpage of the slab 1 by causing the position detecting unit 28 to detect the positions of the pressing rolls 21 when the pair of pressing rolls 21 move in the thickness direction of the slab 1 in a manner following the shape of the slab 1 in a state where the slab 1 is pinched by the pair of pressing rolls 21 by using the continuous casting equipment 10 including the mold 11, the roll segment 13 that is disposed in a plurality of stages below this mold 11 and supports the slab 1 drawn from the mold 11, and the slab warpage detection apparatus 20 that detects warpage of the slab 1 drawn from the mold 11. The continuous casting equipment 10 includes the slab warpage detection apparatus 20 that has the pair of pressing rolls 21 pinching the slab 1 on the exit side of the roll segment 13, the movement units 24 supporting this pair of pressing rolls 21 to be movable in the thickness direction of the slab 1, and the position detecting units 28 detecting the positions of the pressing rolls 21 in the thickness direction of the slab 1; the cutters 15 that cut the slab 1; and the lower conveying rolls 17 that support and convey the slab 1 on a side below the cutters 15.

EXAMPLE

(42) Hereinafter, the results of an experiment performed to confirm the effects of the present invention will be described.

(43) A slab having a rectangular cross section with a thickness of 250 mm and a width of 2,200 mm was subjected to continuous casting using continuous casting equipment (vertical-type continuous casting apparatus) described in the present embodiment.

(44) In Comparative Example, the slab warpage detection apparatus was not provided, and warpage was not straightened.

(45) In Example of the present invention, the slab warpage detection apparatus described in the present embodiment was used. Here, A distance A between a pair of pressing rolls on the upper side and a pair of pressing rolls on the lower side in FIG. 4 was set to 600 mm, and A distance B between the pair of pressing rolls on the lower side and a lower conveying roll was set to 5,660 mm.

(46) In addition, from the past performance, a lower conveying roll, which had a size used when the slab rode an the lower conveying roll and conveyance stopped in a case where the warpage amount of a slab in the lower conveying roll became 30 mm or greater, was used.

(47) In regard to pressing forces of the pair of pressing rolls, pressing forces of both rolls were set to be approximately equal to each other. Specifically, a pressing force of one pressing roll was set to 100 t, and a pressing force of the other pressing roll was set to 92 t.

(48) In addition, in a case where the warpage amount in the lower conveying roll was estimated to be 20 mm or greater, warpage was straightened such that the warpage amount of a slab became 5 mm or smaller by adjusting the positions of the pair of pressing rolls through servo control.

(49) Table 1 shows the comparison results of a situation of Example of the present invention (Example A of the present invention) in which no warpage was generated, a situation (Example B of the present invention) in which warpage was generated, and a situation of Comparative Example in which warpage was generated.

(50) In addition, Table 2 shows the evaluation results of the casting length and the number of conveyance stops due to slab warpage between Example of the present invention and Comparative Example.

(51) TABLE-US-00001 TABLE 1 Example A Example B Comparative of present of present Example invention invention Positions of the pressing rolls on — 0.5 4.3 upper side (mm) Positions of the pressing rolls on — 0.6 9.2 lower side (mm) Warpage amount in lower — 1.6 46.2 conveying rolls (mm) Sensing of warpage of slab x Absent Present Straightening of warpage of slab Absent Absent Present Interference with lower Present Absent Absent conveying rolls

(52) TABLE-US-00002 TABLE 2 Example Comparative of present Example invention Casting length 27,284 23,520 The number of conveyance 3 0 stops due to slab warpage

(53) In Comparative Example, warpage of a slab could not be detected and a slab rode on the lower conveying roll due to warpage of the slab. Then, conveyance of the slab stopped. Such a convey stop occurred three times in the middle of the casting length of 27,284 m.

(54) In contrast, in Example of the present invention, warpage was sensed by the slab warpage detection apparatus at the exit part of the roll segment, and the warpage amount of the position of the lower conveying roll was assumed.

(55) In Example A of the present invention, it was assumed that the warpage amount in the part of the lower conveying roll calculated from the amount of displacement of the position of the pressing roll on the upper side and the amount of displacement of the position of the pressing roil on the lower side became 1.6 mm (smaller than 20 mm). Therefore, even if straightening of warpage was not performed, a slab did not ride on the lower conveying roll, and a convey stop due to warpage of the slab caused in the middle of the casting length of 23,520 m did not occur.

(56) In Example B of the present invention, it was assumed that the warpage amount in the part of the lower conveying roll calculated from the amount of displacement of the position of the pressing roll on the upper side and the amount of displacement of the position of the pressing roll on the lower side became 46.2 mm (20 mm or greater). Therefore, straightening of warpage was performed. Consequently, a slab did not ride on the lower conveying roll, and a convey stop due to warpage of the slab caused in the middle of the casting length of 23,520 m did not occur.

(57) As described above, according to the present invention, it was confirmed that warpage of a slab drawn from a mold was detected in an early stage and the warpage amount thereof could be measured. Accordingly, occurrence of a convey stop due to warpage of a slab can be prevented, and an operation can be stably performed.

BRIEF DESCRIPTION OF THE REFERENCE SYMBOLS

(58) 1 slab 10 continuous casting equipment 11 mold 13 roll segment 14 pinching roll 15 cutter 17 lower conveying roll 20 slab warpage detection apparatus 21 pressing roll 24 movement unit 28 position detecting unit 30 control device