JP2556240Y2 - Slab reduction device in continuous casting - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slab reduction device in continuous casting, and particularly, without causing internal cracks or the like.
The present invention relates to an apparatus capable of reliably preventing center segregation by continuously reducing a cast slab largely.

[0002]

2. Description of the Related Art Continuous casting of steel tends to be widely used because it has higher productivity and is more advantageous in terms of energy than the ingot-bulking method. It is known that in a piece, due to solidification shrinkage near the solidification completion point, molten steel components such as carbon and sulfur are concentrated in the center and center segregation occurs, leading to deterioration of mechanical properties and workability. Have been. In order to reduce or eliminate the above-mentioned defects, a conventional continuous casting facility employs a method in which a portion from a solid-liquid two-phase region of a slab to a solidification completion point is reduced by a fixed type reduction roll.

[0003]

However, in the conventional slab reduction method, if a large reduction amount is to be obtained within a predetermined area (mainly a two-phase area) by one fixed roll, an extremely large roll diameter is required. This is unrealistic in terms of equipment and structure. On the other hand, when trying to reduce the predetermined area by increasing the number of rolls, it is necessary to reduce the roll diameter, and the bending angle with respect to the solidified shell becomes large and internal cracks easily occur. Increasing the number can only slightly cover the structural limitations of a single large diameter roll.

On the other hand, the present inventors have proposed that the pair of reciprocating rolls is gradually increased along the slab drawing line in the upstream direction of the drawing line from the slab solidification completion point, and the casting is performed from the upstream side of the drawing line. The slab is reciprocated repeatedly so as to gradually decrease to the slab solidification completion point, and the portion from the solid-liquid two-phase region of the slab to the solidification completion point is continuously ironed down, thereby continuously casting the slab without causing internal cracks etc. We have developed a slab reduction method that can reliably prevent center segregation by reducing the pressure significantly, and have filed an application. This invention was made in such a situation, and an object of the invention is to provide a slab reduction device for performing the above method.

[0005]

SUMMARY OF THE INVENTION Therefore, a slab reduction device in continuous casting according to the present invention comprises a pair of slab reduction rolls arranged on both sides of a solid-liquid two-phase region of a continuously casting slab. A pair of swing arms, each of which supports a roll, extends in a direction substantially perpendicular to the cast piece, and has a rear end portion rotatably fixed thereto, and an arm drive for repeatedly swinging the pair of swing arms synchronously over a certain angle. The gist of the invention is that the slab reduction locus is mainly composed of the means and the trajectory of both rolls due to the swing of both arms is widened on the upstream side of the slab and narrowed on the downstream side.

Here, the driving speed of the slab pressure reduction roll is set according to the material and type of the slab, the drawing speed of the slab, and the like. For example, when continuously casting a bloom or billet of steel, a drawing speed of 0.3 to 2.5 m / min is often adopted, in which case the diameter is 200 to 500 mm.
Average roll speed of 10 to 60 m / mi
n, can be reciprocated with a stroke of 0.3 m to 1.2 m. The swing angle of the roll may be set based on the length and stroke of the swing arm. For example, the lower limit of the downward swing of a line connecting the rear end connection points of both swing arms (see the dashed line b in FIG. 1). And an angle of 10 to 15 ° upward (see the angle θ in FIG. 1) can be employed.

[0007]

The arm drive means is operated, and the pair of swing arms connects the fixed point of the rear ends of both arms to the lower limit of the downward swing, and synchronizes within a predetermined angle range from there toward the upstream of the slab. When repeatedly swinging the slab, the slab pressure roll reciprocates repeatedly so as to have a wide roll interval on the slab upstream side and a narrow roll interval on the downstream side. Then, since the slab reduction roll shows the same reduction behavior as rolling down the infinite rolls of the same diameter along the trajectory, the entire region from the solid-liquid two-phase region to the solidification completion point As a result of being repeatedly reduced with a very small reduction amount, the region from the solid-liquid two-phase region to the solidification completion point of the continuously cast slab is reduced with a large reduction amount without causing internal cracks.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to specific examples shown in the drawings. FIG. 1 shows a slab reduction device in continuous casting according to an embodiment of the present invention. In the drawing, a mounting base 1 is fixed to a structure (not shown) so as to extend in a direction perpendicular to the casting slab W in the vicinity of a two-phase region of the casting slab W, and near the left and right ends of the mounting base 1. One end of a substantially L-shaped swinging plate 2 is swingably connected to the mounting bracket 1a by a connecting pin 2a, and a roll gap adjusting cylinder 3 is mounted on both ends of the mounting base 1 by a mounting pin 3a. This is also attached so as to be swingable, and the other end of the swing plate 2 is swingably connected to the tip end of the piston rod 3b of the cylinder 3 by a connecting pin 2b. The rear ends of the short and long swing arms 4 and 5 are swingably connected to a substantially central portion of the swing plates 2 by connecting pins 2c, respectively. The shaft 6a of one slab pressure reduction roll 6 is rotatably supported on the upper side near the tip of the short swing arm 4, and the other side is substantially at the center lower side of the long swing arm 6. The shaft 6a of the slab reduction roll 6 is rotatably supported. Note that the above-described roll gap adjusting cylinder and the swing plate 2 are for adjusting the roll gap,
It is not always necessary, and the rear ends of the swing arms 4 and 5 may be directly connected to the mounting bracket 1a. Also,
A driving cylinder (arm driving means) 7 is swingably mounted inside the left mounting bracket 1a of the mounting base 1 by a mounting pin 7a, and the long swing arm 5 is attached to a tip end of a piston rod 7b of the cylinder 7. Are pivotally connected by a connecting pin 7b. A link 8 is swingably connected between a central portion of the long swing arm 5 and a distal end of the short swing arm 4 by connecting pins 8a and 8b. In a substantially contracted state, a line a connecting the roll connecting pin 6a and the arm connecting pin 2c on both sides substantially coincides with a line b connecting the both side connecting pins 2c, that is, substantially perpendicular to the slab W. Has become.

In the above-described configuration, when the piston rod 7b of the drive cylinder 7 extends, the long swing arm 5 swings upward by a predetermined angle around the connecting pin 2c at the rear end. The connected short swing arm 4 also swings upward around the rear end connecting pin 2c, and the pressing rolls 6 on both sides of the slab synchronously move upward so as to increase the roll interval. When the piston rod 7b of the drive cylinder 7 contracts from that state, the long swing arm 5 and the short swing arm 4 swing downward by a predetermined angle around the connecting pin 2c, and the pressing rolls 6 on both sides of the slab are now The roll moves downward so as to reduce the gap, and the region from the solid-liquid two-phase region of the slab W to the solidification completion point is repeatedly reduced.

More specifically, referring to FIG. 2, the swing arms 4 and 5 are driven by the driving cylinder 7 at a predetermined speed in a rolling region A from the solid-liquid two-phase region on the slab drawing line to the solidification completion point W1. By repeatedly swinging at a predetermined angle θ, the pair of slab pressure reduction rolls 6 is moved from the solidification completion point W1 to the upstream along the outer surface of the roll (rolling equivalent roll) having a radius equal to the distance between the connecting pins 2c and 6a. Trajectory C that gradually increases and conversely decreases toward solidification completion point W1
1. Swing C2 back and forth. The trajectories C1 and C2 can take free curves by changing the intervals and positions of the connecting pins 2c and 6a. As shown in FIG. 2, when the slab W is pulled out of the mold in the state of the solidified shell WS and the molten metal WL, and reaches the rolling region A from the solid-liquid two-phase region to the solidification completion point W1, the solid-liquid of the slab W Solidification completion point W1 from two-phase region
Is lowered while being continuously squeezed by the reciprocating rocking roll 6 described above. In the conventional rolling method using a fixed roll, in order to reduce the slab W without causing internal cracks, it is necessary to keep the actual strain of the slab W within 1%. For example, slab size: 380 × 490 mm, slab drawing speed: 0.5 m / min, fixed roll diameter: φ400
Although the reduction amount in the case of rolling down by mm is 3 to 4 mm, the center reduction cannot be largely improved by such reduction amount. On the other hand, as in the present invention, when the slab reduction roll 6 is reciprocally oscillated and ironed down, the reduction amount per reciprocation can be reduced to reduce the actual distortion amount. As a whole, a large amount of reduction can be obtained, and center segregation can be greatly improved.

When the width of the slab W is changed,
The distance between the rear end connecting pins 2c of the swing arms 4 and 5 may be adjusted by expanding and contracting the piston rod 3b of the roll interval adjusting cylinder 3 and swinging the swing plate 2 around the connecting pin 2a. When an abnormality occurs in the slab reduction roll 6 for some reason, the piston rod 3b of the roll gap adjusting cylinder 3 is contracted, and the slab reduction rolls 6 on both sides are retracted beyond the width of the slab W. A normal continuous casting operation can be performed without interrupting the casting operation.

An example of the embodiment is as follows. FIG.
, Slab size: 380 × 490 mm, slab drawing speed: 0.5 m / min or more, reduction roll diameter: 400
φmm, roll roll swing angle θ: 10 °, roll swing distance L: 816 mm, roll equivalent roll diameter R: 4676 φ
mm, the average speed of the reciprocating motion: 12 m / min, and the maximum reduction d1: 20 mm. When the actual strain in this case is calculated, the actual strain is 0.3%, and a large reduction can be obtained at a low distortion speed. I can understand.

[0013]

As described above, according to the slab reduction device in continuous casting according to the present invention, the reduction device can be easily configured, and the solid-liquid state of the slab is independent of the type of the continuous casting equipment. The region from the two-phase region to the solidification completion point could be greatly reduced with a low strain rate, the center segregation of the slab was reliably prevented without any internal cracking, and a slab with few defects could be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a slab reduction device in continuous casting according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the above device.

FIG. 3 is a diagram for explaining an example of an embodiment of the above device.

[Explanation of symbols]

 4 Short swing arm 5 Long swing arm 6 Slab reduction roll 7 Drive cylinder (arm drive means)

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Ichiro Fukumoto 3007 character, Nakajima character, Shima, Himeji City, Hyogo Prefecture Inside Sanyo Special Steel Co., Ltd. (56) References JP-A-61-14058 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] 1. A pair of slab pressure reduction rolls 6 disposed on both sides of a solid-liquid two-phase region of a slab being continuously cast, each of which supports the rolls 6 and extends in a direction substantially perpendicular to the slab W. A pair of swing arms 4 whose rear ends are freely rotatable
5 and an arm driving means 7 for repeatedly and synchronously swinging the pair of swing arms 4 and 5 over a certain angle. The interval between the trajectories of the two rolls 6 caused by the swing of the two arms 7 is wide on the upstream side of the slab. A slab reduction device for continuous casting, wherein a slab reduction trajectory that narrows downstream is taken.