JP2014200816A - Method and apparatus for determining solidification completion position of cast metal, and method for producing cast metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and stably determine a solidification completion position of a cast metal regardless of the type of a continuous casting machine, without requiring large modification thereof,.SOLUTION: An apparatus for determining a solidification completion position extends to the outside of a segment chamber 27 for storing soft reduction segments A to C, uses laser range finders 30A to 30C to measure, at the outside of the segment chamber 27, the displacement amount of rotary shafts 28a for rotationally driving pinch rolls 25a provided in the respective soft reduction segments A to C, and determines the solidification completion position of the cast metal by comparing the measured displacement amounts of the rotary shafts 28a of the respective soft reduction segments with each other. Thereby, the solidification completion position of the cast metal can be easily and stably determined regardless of the type of the continuous casting machine, without requiring large modification thereof.

Description

  The present invention relates to a slab solidification completion position determination method, a slab solidification completion position determination device, and a slab manufacturing method for determining a solidification completion position of a slab in a continuous casting machine.

  Generally, in order to improve the productivity of a continuous casting machine, it is necessary to increase the casting speed. However, when the casting speed is increased, the solidification completion position (crater end position) of the slab moves from the mold meniscus position to the downstream side in the casting direction. And if the solidification completion position of the slab exceeds the setting range of the slab support roll, bulging occurs where the slab swells due to the action of static iron pressure, and if the deterioration of internal quality or bulging is enormous Problems such as casting stop occur.

  From such a background, a method for determining a solidification completion position of a slab has been proposed. Specifically, Patent Documents 1 to 3 describe a method of determining a solidification completion position of a slab using a property in which an ultrasonic propagation time varies depending on a slab temperature. Patent Documents 4 and 5 describe a method in which a load detection sensor such as a strain gauge is provided on a slab support roll, and a solidification completion position of the slab is determined based on a change in load acting on the slab support roll. Yes. Patent Document 6 describes a method of determining the solidification completion position of a slab from the amount of displacement of a rolling roll. Patent Document 7 describes a method of determining a solidification completion position of a slab from the amount of displacement of a column portion that connects an upper frame and a lower frame of a reduction segment.

JP 2002-14083 A JP 2012-215413 A Japanese Patent Laid-Open No. 62-148850 JP-A-9-225661 Special table 2011-506101 gazette JP 2002-66704 A JP 2012-110947 A

  However, the slab solidification completion position determination method described in Patent Documents 1 to 7 has the following problems. That is, according to the methods described in Patent Documents 1 to 3, the ultrasonic sensor must be installed in the vicinity of the slab, so that the apparatus becomes large and, in principle, within a few meters in the vicinity of the ultrasonic sensor. Only certain solidification completion positions can be determined with high accuracy. According to the methods described in Patent Documents 3 and 4, it is difficult to install the load detection sensor, and the load detection sensor is fragile, so that it is very difficult to handle.

  The method described in Patent Document 6 can be applied only to a continuous casting machine that can measure the amount of displacement of all the rolling rolls. In the methods described in Patent Documents 1 to 6, since the measurement must be performed in a harsh high-temperature steam environment in the segment chamber in which the reduction segment is accommodated, there is a high risk of sensor failure. In the method described in Patent Document 7, the amount of displacement of the support column is the amount of displacement of the entire rolling-down segment, which is as small as 1 mm or less, so it is difficult to accurately determine the solidification completion position due to the influence of disturbance.

  The present invention has been made in view of the above, and the object thereof is simple and stable solidification completion position of a slab, without requiring a major modification regardless of the type of continuous casting machine. It is an object to provide a solidification completion position determination method and a solidification completion position determination apparatus for a slab that can be determined. Another object of the present invention is to provide a slab manufacturing method capable of improving the slab productivity.

  A solidification completion position determination method for a slab according to the present invention is a slab solidification completion position determination method for determining a solidification completion position of a slab in a continuous casting machine having a plurality of light reduction segments. A measuring step for measuring the amount of displacement of the rotating shaft that rotates outside the segment chamber and rotates the pinch roll provided in the lightly pressed segment outside the segment chamber, and each lightly pressed segment measured in the measuring step And a determination step of determining a solidification completion position of the slab by comparing the amount of displacement of the rotation axis.

  In the slab solidification completion position determining method according to the present invention, in the above invention, in the determination step, the solidification of the slab is completed in a region where the amount of change in the amount of displacement of the rotary shaft between the segments under light pressure is not more than a predetermined value. The step of determining the position is included.

  The solidification completion position determination method for a slab according to the present invention is the laser distance meter according to the above invention, wherein the measurement step is disposed outside a segment chamber and measures a distance between the rotating shaft and the disposed position. And measuring the amount of displacement of the rotating shaft by using.

  A slab solidification completion position determination device according to the present invention is a slab solidification completion position determination device for determining a solidification completion position of a slab in a continuous casting machine having a plurality of light reduction segments, Measuring means for measuring the amount of displacement of the rotating shaft that rotates outside the segment chamber and rotates the pinch roll provided in the light pressure segment, outside the segment chamber, and each light pressure segment measured by the measurement means And determining means for determining the solidification completion position of the slab by comparing the amount of displacement of the rotation shaft.

  The method for producing a slab according to the present invention is a slab production method for producing a slab by using a continuous casting machine having a plurality of lightly reduced segments, and extends outside a segment chamber that accommodates the lightly reduced segments. By comparing the measurement step of measuring the amount of displacement of the rotating shaft that rotationally drives the pinch roll provided in the lightly pressed segment outside the segment chamber with the amount of displacement of the rotating shaft of each lightly pressed segment, Determining the solidification completion position, and manufacturing the slab by controlling the operating conditions of the continuous casting machine based on the solidification completion position of the slab determined in the determination step. Features.

  According to the slab solidification completion position determination method and solidification completion position determination apparatus according to the present invention, the solidification of the slab can be performed easily and stably without requiring a major modification regardless of the type of the continuous casting machine. The completion position can be determined. Moreover, according to the manufacturing method of the slab which concerns on this invention, productivity of a slab can be improved.

FIG. 1 is a schematic diagram showing a configuration of a continuous casting machine to which a slab solidification completion position determination system according to an embodiment of the present invention is applied. FIG. 2 is a side view showing the configuration of the lightly pressed segment viewed from a direction orthogonal to the casting direction in a horizontal plane. FIG. 3 is a side view showing the configuration of the lightly pressed segment viewed from the casting direction. FIG. 4 is a block diagram showing a configuration of a slab solidification completion position determination system according to an embodiment of the present invention. FIG. 5 is a diagram for explaining a slab solidification completion position determination method according to an embodiment of the present invention. FIG. 6 is a diagram for explaining a slab solidification completion position determination method according to an embodiment of the present invention.

  Hereinafter, a slab solidification completion position determination system according to an embodiment of the present invention will be described with reference to the drawings.

[Construction of continuous casting machine]
First, a configuration of a continuous casting machine to which a slab solidification completion position determination system according to an embodiment of the present invention is applied will be described with reference to FIG. FIG. 1 is a schematic diagram showing a configuration of a continuous casting machine to which a slab solidification completion position determination system according to an embodiment of the present invention is applied.

  As shown in FIG. 1, a continuous casting machine 1 to which a slab solidification completion position determination system according to an embodiment of the present invention is applied, injects and solidifies molten steel 2, and changes the outer shell shape of the slab 3. A mold 4 for forming is provided. Above the mold 4, a tundish 5 for relaying and feeding the molten steel 2 supplied from a ladle (not shown) to the mold 4 is installed. A sliding nozzle 6 for adjusting the flow rate of the molten steel 2 is provided at the bottom of the tundish 5, and an immersion nozzle 7 is installed on the lower surface of the sliding nozzle 6.

  A cooling grid 8 is disposed below the mold 4, and a plurality of pairs of slab support rolls 9 including a support roll, a guide roll, and a pinch roll are disposed downstream of the cooling grid 8 in the casting direction. In the range of the cooling grid 8 and the gap between the slab support rolls 9 adjacent to the casting direction, a secondary cooling zone in which spray nozzles such as a water spray nozzle and an air mist spray nozzle are arranged is provided. The slab 3 is cooled while being drawn in the casting direction by the cooling water sprayed from the spray nozzle.

  A plurality of transport rolls 10 for transporting the slab 3 are provided on the downstream side in the casting direction of the slab support roll 9 at the most downstream position in the casting direction. A slab cutting machine 11 for cutting a slab 3 a having a predetermined length from the slab 3 is disposed above the transport roll 10. On the upstream side and the downstream side in the casting direction with the solidification completion position 12 of the slab 3 interposed therebetween, the interval between the slab support rolls 21 (see FIG. 2) facing each other with the slab 3 interposed therebetween is directed toward the downstream side in the casting direction. A plurality of lightly under-pressed segments A to C set so as to be narrowed sequentially are installed. The configuration of the lightly under-pressed segments A to C will be described later.

  When the slab 3 is manufactured using the continuous casting machine 1 having such a configuration, first, the molten steel 2 is injected into the tundish 5 from a ladle (not shown) to obtain a predetermined amount in the tundish 5. Molten steel 2 is retained. Next, the molten steel 2 is injected into the mold 4 through the immersion nozzle 7. The molten steel 2 poured into the mold 4 is cooled to form a solidified shell 13 in the outer shell, and is supported by the cooling grid 8 and the slab support roll 9 as a slab 3 having an unsolidified layer 14 inside. Is continuously pulled out below. The thickness of the solidified shell 13 of the slab 3 is increased by being cooled with cooling water from the secondary cooling zone while passing through the slab support roll 9, and solidification to the inside is completed at the solidification completion position 12. . Thereafter, the slab 3 that has been solidified to the inside is cut by the slab cutting machine 11 to become a slab 3a.

[Composition of lightly pressed segment]
Next, with reference to FIG. 2 and FIG. FIG. 2 is a side view showing the configuration of the lightly pressed segment viewed from a direction orthogonal to the casting direction in a horizontal plane. FIG. 3 is a side view showing the configuration of the lightly pressed segment viewed from the casting direction. In the following description, the casting direction is defined as the x direction, the direction perpendicular to the x direction in the horizontal plane is defined as the y direction, and the direction perpendicular to the x direction and the y direction (vertical direction) is defined as the z direction.

  As shown in FIG. 2, the lightly under-pressed segments A to C pass through a pair of frames 22 a and 22 b that respectively hold eight slab support rolls 21 arranged in the x direction, and a pair of frames 22 a and 22 b. And four tie rods 23. Each tie rod 23 is provided with a worm jack 24, and by driving the worm jack 24, the tie rod 23 is extended to adjust the interval between the pair of frames 22a and 22b, that is, the roll interval of the slab support roll 21. be able to.

  Of the eight slab support rolls 21 provided on the pair of frames 22a and 22b, the slab support roll 21 disposed on the most upstream side in the casting direction is a pinch roll (drive roll) 25a and 25b. . The pinch rolls 25a and 25b are connected to rotary shafts 28a and 28b extending outside the segment chamber 27 that accommodates the lightly compressed segments A to C, respectively. The rotation shafts 28a and 28b rotate the pinch rolls 25a and 25b with the y direction as the rotation axis direction. By rotating the rotary shafts 28a and 28b using the drive mechanisms 29a and 29b, the pinch rolls 25a and 25b pull out the slab in the x direction while sandwiching the slab.

  The pinch roll 25a provided on the upper frame 22a side is provided with a hydraulic reduction mechanism 26 so that only the pinch roll 25a can perform the reduction setting. The remaining seven slab support rolls 21 provided on the pair of frames 22a and 22b respectively have a common hydraulic pressure reduction mechanism (not shown), and the seven slab support rolls 21 are integrated and reduced. It can be set.

[Coagulation completion position judgment system]
Next, with reference to FIG. 4, the structure of the solidification completion position determination system of the slab which is one Embodiment of this invention is demonstrated.

  FIG. 4 is a block diagram showing a configuration of a slab solidification completion position determination system according to an embodiment of the present invention. As shown in FIG. 4, the slab solidification completion position determination system according to an embodiment of the present invention includes laser distance meters 30A, 30B, and 30C and a solidification completion position determination apparatus 40. The laser rangefinders 30A to 30C are respectively disposed outside the segment chambers 27 of the lightly underpressure segments A to C (see FIG. 3).

  The laser distance meters 30 </ b> A to 30 </ b> C measure the distance D between the rotation shaft 28 a extending outside the segment chamber 27 and the arrangement position, and input the measured value of the distance D to the coagulation completion position determination device 40. The coagulation completion position determination device 40 is configured by an information processing device such as a personal computer, and performs a coagulation completion position determination process described later, thereby distance between the rotation shaft 28a and the positions where the laser distance meters 30A to 30C are disposed. D is used to determine the solidification completion position of the slab.

[Coagulation completion position judgment process]
Next, with reference to FIG. 5 and FIG. 6, the flow of the solidification completion position determination process of the slab by the solidification completion position determination system will be described.

  When a reduction force is applied to the slab along the z direction using the light reduction segments A to C, a reaction force due to the reduction of the slab acts on the pinch rolls 25a and 25b in the z direction. For this reason, the rotating shafts 28a and 28b connected to the pinch rolls 25a and 25b are displaced in the z direction by a reaction force caused by pressing down the slab. Therefore, the magnitude of the reaction force due to the slab reduction can be confirmed by measuring the amount of displacement in the z direction of the rotary shafts 28a, 28b accompanying the slab reduction. On the other hand, the magnitude of the reaction force by reducing the slab decreases or increases according to the solidified state of the slab, and becomes a constant value when the slab is solidified. Whether the reaction force decreases or increases depends on the casting conditions such as the cross-sectional dimension of the slab.

  Therefore, in the solidification completion position determination system, in the steady state in which the slab is manufactured, first, the solidification completion position determination device 40 uses the laser distance meters 30A to 30C to rotate the rotary shaft 28a and the laser distance meters 30A to 30A. The distance D between the arrangement position of 30C and the displacement amount in the z direction of the rotating shaft 28a is measured. Next, as shown in FIGS. 5 and 6, the coagulation completion position determination device 40 indicates the point P <b> 1 indicating the amount of displacement of the rotating shaft 28 a of the lightly under-pressed segment A, and the amount of displacement of the rotating shaft 28 a of the lightly-underpressed segment B. A curve L1 or a curve L2 passing through the point P2 and the point P3 indicating the amount of displacement of the rotating shaft 28a of the lightly under-pressed segment C is calculated.

  Then, the solidification completion position determination device 40 determines a region where the slope of the curve L1 or the curve L2 is equal to or less than a predetermined value, that is, a region where the change amount of the reaction force due to the slab reduction is equal to or less than the predetermined value as the solidification completion position. judge. For example, in the example shown in FIG. 5, when the slope of the region between the point P2 and the point P3 of the curve L1 is equal to or less than a predetermined value, the coagulation completion position determination device 40 determines the pinch rolls 25a and 25b of the lightly pressed segment B and It is determined that the solidification completion position of the slab is in the region between the pinch rolls 25a and 25b of the lightly pressed segment C. Thereafter, the slab productivity can be improved by manufacturing the slab by controlling the operating conditions such as the casting speed based on the solidification completion position of the slab.

  As is apparent from the above description, in the coagulation completion position determination system according to an embodiment of the present invention, the coagulation completion position determination device 40 extends out of the segment chamber 27 that accommodates the lightly under-pressed segments A to C, Measure the displacement of the rotating shaft 28a that rotationally drives the pinch roll 25a provided in the rolling-down segments A to C outside the segment chamber 27, and compare the measured displacement of the rotating shaft 28a of each light-rolling segment. Thus, the solidification completion position of the slab is determined. Thereby, regardless of the type of the continuous casting machine, the solidification completion position of the slab can be determined easily and stably without requiring significant modification.

  The embodiment to which the invention made by the present inventors is applied has been described above, but the present invention is not limited by the description and the drawings that constitute a part of the disclosure of the present invention. For example, when there is a possibility that the rotating shaft 28a is bent by its own weight, the distance D between the rotating shaft 28a and the positions where the laser distance meters 30A to 30C are disposed is calibrated in consideration of the amount of bending of the rotating shaft 28a. It is desirable to do. As described above, other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Continuous casting machine 2 Molten steel 3 Cast piece 4 Mold 5 Tundish 6 Sliding nozzle 7 Immersion nozzle 8 Cooling grid 9 Cast piece support roll 10 Conveyance roll 11 Cast piece cutting machine 12 Solidification completion position 21 Cast piece support roll 22a, 22b Frame 23 Tie rod 24 Warm jack 25a, 25b Pinch roll (drive roll)
26 Hydraulic pressure reduction mechanism 27 Segment chamber 28a, 28b Rotating shaft 29a, 29b Drive mechanism 30A, 30B, 30C Laser distance meter 40 Solidification completion position determination device A, B, C Light pressure reduction segment

Claims (5)

A slab solidification completion position determination method for determining a solidification completion position of a slab in a continuous casting machine including a plurality of lightly reduced segments,
A measurement step of measuring the amount of displacement of the rotating shaft that extends outside the segment chamber that accommodates the lightly compressed segment and rotationally drives the pinch roll provided in the lightly compressed segment, outside the segment chamber;
A determination step of determining a solidification completion position of the slab by comparing the amount of displacement of the rotation axis of each lightly-under-pressed segment measured in the measurement step;
The solidification completion position determination method of the slab characterized by including these.   2. The determination step according to claim 1, wherein the determination step includes a step of determining a region where the amount of change in the amount of displacement of the rotating shaft between segments under light pressure is a predetermined value or less as a solidification completion position of a slab. A method for determining the solidification completion position of a slab.   The measuring step includes a step of measuring a displacement amount of the rotating shaft using a laser distance meter that is disposed outside the segment chamber and measures a distance between the rotating shaft and the disposed position. 3. A method for determining a solidification completion position of a slab according to claim 1 or 2. A slab solidification completion position determination device for determining a solidification completion position of a slab in a continuous casting machine having a plurality of lightly reduced segments,
Measuring means for measuring the amount of displacement of the rotating shaft that extends outside the segment chamber that accommodates the lightly pressed segment and rotationally drives the pinch roll provided in the lightly pressed segment, outside the segment chamber;
Determining means for determining the solidification completion position of the slab by comparing the amount of displacement of the rotary shaft of each lightly-underscored segment measured by the measuring means;
A slab solidification completion position determination device comprising: A slab manufacturing method for manufacturing a slab using a continuous casting machine having a plurality of lightly reduced segments,
A measurement step of measuring the amount of displacement of the rotating shaft that extends outside the segment chamber that accommodates the lightly compressed segment and rotationally drives the pinch roll provided in the lightly compressed segment, outside the segment chamber;
A determination step of determining the solidification completion position of the slab by comparing the amount of displacement of the rotating shaft of each lightly-under-pressed segment;
Producing a slab by controlling the operating conditions of the continuous casting machine based on the solidification completion position of the slab determined in the determination step;
The manufacturing method of the slab characterized by including this.

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